LX470 AHC issues - pressure sensor 1998 Vs. 2002 (2 Viewers)

[IndroCruise]

UPDATE << 7/27>> 11:30

I just had a NEW issue and it's with the B+ signal on Techstream. It's Way low, @ 1.7 V !! Where does B+ V come from and should I check the AHC computer connector S6 pins? If so,... Which PINs do I check ? Any voltage < 10.0 V WILL cause an error code 1731 - which is a fail-safe for the front leveling valve. This was JUST working yesterday!! Geez............ I'm going backward now....!
View attachment 3687498

No -- you are not going backwards -- this is new and useful information -- so you are going forward!!

However, understandable frustration also is leading to distraction and causing speculation on new causes without first dealing properly with those more likely causes already identified.

As already explained (in various different ways) by @suprarx7nut, @Moridinbg, @IndroCruise, and @2001LC in this thread and elsewhere, intermittent faults showing loss of B+ voltage as described indicate loss of continuity at a connector or a broken wire (usually near a connector or sometimes due to heat damge to wiring from the exhaust or sometimes from vermin attacking wiring).

Intermittency means that a circuit is making or breaking intermittently as the break makes contact and loses contact due to changes in temperature or movements.

When this happens, it is not unusual to receive strange DTC indications from Techstream or other scanner -- such as DTC C1762 or DTC C1731 as has happened in this case.

If the solenoids test out OK for continuity per FSM procedure at the terminals of the Control Valve Assembly, the next essential step is to use an ohm-meter and the Electrical Wiring Diagram (EWD) provided at Post #154 to pursue continuity further back in the circuit. As @suprarx7nut and others have highlighted, repeating this same test further back in the circuit (such as at the BI1 connector) should show similar resistance in ohms to the values found directly at the Control Valve Assembly. If not, there is a problem at a connector or there is a damaged wire -- and whatever it is it has to be found or bypassed as shown in the mark-up by @suprarx7nut.

Only when the health of the relevant circuits has been confirmed (meaning continuity has been checked and rectified if necessary) is it worthwhile to pursue causes elsewhere.

Way back in this thread, there are useful posts with pictures by @2001LC referring to his experiences at or near the BI1 connector. In a recent Post elsewhere, @Moridinbg has described an experience in overcoming a nearby broken wire at or near the BI1 connector.

Suggest proceed systematically, accessing at BI1, pursuing continuity using an ohm-meter and tracing circuits back to the Control Valve Assembly until satisfied that this circuit is intact. Given that there is an intermittent problem, it will be important to "wiggle" wiring and connectors while testing to try to explore the location of the intermittent discontinuity.

 

[2001LC]

Yep. Intermittent short are a bear to isolate.

The short needs to be happening while testing, or at least we need to get eyeballs in some wire or wire block, that looks less than optimal.

Once in and AC issue (just as example), many shops had hunted and replaced most every part of the AC system. After years and about a 1/2 dozen shops tried to fix the AC, to no avail. It came to me. In 5 minutes I made and assume of a short, due to water entry in the past (had since been stopped). I did ~10 hours of diagnostic work, lust making sure all others before me, didn't miss anything. They didn't, at least not within the AC system.
Then back to my assumption of water entry. I found the smallest amount of oxidation on the prongs of just few fuses out of the many, in RH junction box. That was a confirmation of water entry. Ultimately is was the ground fault signal of RH junction box with oxidation, causing the whole issue.

The most difficult AHC diagnostic & repair I did. Was an intermittent fault, in wire housing block under rear LH quarter tip. What made it even more difficult, was it wasn't the only issues in the AHC system.

Bottom line: Check every wire housing block, along with all wires for any discoloration, breaks, continuity & resistance issues.

 

[Moridinbg]

Check continuity If the valves are not opening each and every time right on point, you can't expect the hydraulic system to work.

 

[suprasvobodea]

Check continuity If the valves are not opening each and every time right on point, you can't expect the hydraulic system to work.

<<< Update 7/28 2:;25

Moridinbg, INDOCRUISE


You know, the more I analyze and pray about this, the more I start to think it's intermittent electrical issues. THe fact that you said "every time I see alow B+ issue, it's wire related. Well, I have never had an issue with this or got a 1731 code until yesterday, and guess what, Today, there is NO problem with B+/ its 12.3V! << WHY..?
Next, the LX raised several inches in front and worked ! The rear didn't but I was happy for a 50% improvement in success! . Only later that same day, it would NOT pump, I kept getting 1762 immediately after doing ACTIVE test >> just like I have for the past 4 months. forgot to mention, when I had the front globes pressurized to 11, I did a lot of front bleeding, There was one puff of air, but I slowly bleed for 10 seconds and NO bubbles!. for either front globe! There was a brief push of bubble oil in rears (expected) , but they went dead in a few seconds.. ( NO PRESSURE there!)

This is the worst type of problem for me. Intermittent Electrical! I am a Mechanical Project Engineer and great with intuitive mechanical aptitude. However....electrical, especially, Electrical intermittent... this is where I get my butt kicked. So to help me, this is my plan below..........


I have created a multipoint, orderly, logical progressing plan to get this damn thing solved & fixed;.. TODAY!

1. SInce the return valve has shown that it was plugged already, & INDOCRUISE suggested that I probably have disturbed the system with ..: "contaminants" then it's possible it could become "Re-plugged " again! So, here are my steps;

STEP I ( Electrical Continuity)

1. Disconnect the outlet line and try to block oil with direct 12V to check the return valve function.

2. Checking continuity : *(Per Indocruise and yourself ) of the following in order starting with all 4 connectors in series from Control valve Assy >>>back to AHC ECU & if that has full continuity /1-2 Ohm reading ..then I know that is NOT the problem. HOWEVER,. if the "suspect rear leveling valve wire has high resistance,...then THAT IS WHERE THE PROBLEM IS AND CAN BE ISOLATED BY USING FEWER CONNECTORS IN SERIES CHAIN!

A. Checking 5 wires at control valve connector >>>>> to ECU Connector
B. Checking 5 wires from ECU Connector >>Bl1 connector
C. Checking 5 wires from Control Valve assy connector >> BI1 Connector ( I already did this for just the REAR gage & Level wires and were 2 ohms - all good. will check the FRONT valve and gate wires as well ... just to be sure but those are working when I press the ACTIVE test feature on Techstream

STEP II (Mechanical)

Apply 12 V direct to Pump, while applying 12V to Rear Level Soenoid pin #5. QUESTION >>> Do I need to have the engine running while doing this or just ignition ON?

Please let me know your thoughts, comments, and input as to what you guys think?! ASAP if possible. I am going back out now, to start the electrical troubleshooting......

 

[suprarx7nut]

@suprasvobodea Did you check for a short to ground on that BI1 connector as well?

You can have a complete dead short to ground and still get good resistance so it's important to check each of the pins for resistance to ground. It should be "OL" for all those.

Are you bleeding the rear and then the height accumulator any time you're able to get it up in the air? I would until you can go 3-4 times in a row with not a single trace of a bubble. I still think trapped air may be messing you quite a bit.

In my experience the circuit faults often have another code associated with it. It's not impossible, but it is unusual to have a control valve, sensor or switch wiring fault without a code to go along with it. Toyota did a pretty good job putting logic on most the conductors.

 

[IndroCruise]

<<< Update 7/28 2:;25

Moridinbg, INDOCRUISE


You know, the more I analyze and pray about this, the more I start to think it's intermittent electrical issues. THe fact that you said "every time I see alow B+ issue, it's wire related. Well, I have never had an issue with this or got a 1731 code until yesterday, and guess what, Today, there is NO problem with B+/ its 12.3V! << WHY..?
Next, the LX raised several inches in front and worked ! The rear didn't but I was happy for a 50% improvement in success! . Only later that same day, it would NOT pump, I kept getting 1762 immediately after doing ACTIVE test >> just like I have for the past 4 months. forgot to mention, when I had the front globes pressurized to 11, I did a lot of front bleeding, There was one puff of air, but I slowly bleed for 10 seconds and NO bubbles!. for either front globe! There was a brief push of bubble oil in rears (expected) , but they went dead in a few seconds.. ( NO PRESSURE there!)

This is the worst type of problem for me. Intermittent Electrical! I am a Mechanical Project Engineer and great with intuitive mechanical aptitude. However....electrical, especially, Electrical intermittent... this is where I get my butt kicked. So to help me, this is my plan below..........


I have created a multipoint, orderly, logical progressing plan to get this damn thing solved & fixed;.. TODAY!

1. SInce the return valve has shown that it was plugged already, & INDOCRUISE suggested that I probably have disturbed the system with ..: "contaminants" then it's possible it could become "Re-plugged " again! So, here are my steps;

STEP I ( Electrical Continuity)

1. Disconnect the outlet line and try to block oil with direct 12V to check the return valve function.

2. Checking continuity : *(Per Indocruise and yourself ) of the following in order starting with all 4 connectors in series from Control valve Assy >>>back to AHC ECU & if that has full continuity /1-2 Ohm reading ..then I know that is NOT the problem. HOWEVER,. if the "suspect rear leveling valve wire has high resistance,...then THAT IS WHERE THE PROBLEM IS AND CAN BE ISOLATED BY USING FEWER CONNECTORS IN SERIES CHAIN!

A. Checking 5 wires at control valve connector >>>>> to ECU Connector
B. Checking 5 wires from ECU Connector >>Bl1 connector
C. Checking 5 wires from Control Valve assy connector >> BI1 Connector ( I already did this for just the REAR gage & Level wires and were 2 ohms - all good. will check the FRONT valve and gate wires as well ... just to be sure but those are working when I press the ACTIVE test feature on Techstream

View attachment 3688647

STEP II (Mechanical)

Apply 12 V direct to Pump, while applying 12V to Rear Level Soenoid pin #5. QUESTION >>> Do I need to have the engine running while doing this or just ignition ON?

Please let me know your thoughts, comments, and input as to what you guys think?! ASAP if possible. I am going back out now, to start the electrical troubleshooting......

Firstly, as a base-line, what actual readings in ohms did you get when doing FSM test procedure directly between terminal 2 and each of the other four terminals at the Control Valve Assembly?

Secondly, when applying power directly to terminal 2 and terminal 5 of the Control Valve Assembly, the connector is (or should be) removed and the Control Valve Assembly is electronically isolated -- so neither the ignition nor engine need to be "ON". The purpose in this 'workaround' is ONLY to apply Pump pressure (by direct 12 volt connection to the AHC Pump) THROUGH the Levelling Valve (which has been opened by direct connection) to the 'shock absorbers' to raise the Rear of the vehicle AND ALSO to provide an opportunity to clear the hydraulic line by opening a Rear bleeder valve.

The AHC system is NOT active in this 'workaround'.

NOTE: The Height Control Accumulator is not activated in this 'workaround' -- the solenoid valve remains closed and fluid flows directly to the Control Valve Assembly. Fluid passes through the Levelling Valves in the Control Valve Assembly if the "normally closed" Levelling Valves actually are open. The Gate Valves in the Control Valve Assembly are "normally open" when the vehicle is at rest.

The point of the 'workaround' is to get the vehicle raised so that efforts of bleeding air can begin PROVIDED THAT any electrical discontinuities or short circuits first have been discovered and resolved.

 

[suprasvobodea]

@suprasvobodea Did you check for a short to ground on that BI1 connector as well?

You can have a complete dead short to ground and still get good resistance so it's important to check each of the pins for resistance to ground. It should be "OL" for all those.

Are you bleeding the rear and then the height accumulator any time you're able to get it up in the air? I would until you can go 3-4 times in a row with not a single trace of a bubble. I still think trapped air may be messing you quite a bit.

In my experience the circuit faults often have another code associated with it. It's not impossible, but it is unusual to have a control valve, sensor or switch wiring fault without a code to go along with it. Toyota did a pretty good job putting logic on most the conductors.

SupraRXnut

Im apologize, but I do not understand your question " Dead short to ground on the Bl1 connector ". Check each of the pins for resistance to ground " Please describe what I must do at that Bl1 connector and which end ( female (Larger ) or male (smaller) side.

 

[suprarx7nut]

SupraRXnut

Im apologize, but I do not understand your question " Dead short to ground on the Bl1 connector ". Check each of the pins for resistance to ground " Please describe what I must do at that Bl1 connector and which end ( female (Larger ) or male (smaller) side.

I don't recall which terminal end goes to the valve, but the manual should tell you. Those << arrows in the diagram you posted tell you which gender the terminals are on each side. You want the measure the valve side. I think you can also see the wire runs. One end goes into the cab, the other runs up along the exterior underside.

You need to measure from your wire in question to ground (any ground - could be a white/black wire in the harness or the actual vehicle frame or any bolt attached to it). I guess you're concerned about Black - Orange on pin 9 and Black - Red on pin 7.

One of the more common failures is the insulation rubbing raw on the frame. That will produce a short to ground before it fails "open circuit". Meaning, until the wire rubs itself apart completely, you can pass a resistance check, but when the ECU tries to actually send an electrical signal (like the signal to open a valve) the electrical power needed to move the valve/solenoid leaks out of the conductor into the frame.

Not sure if that electrical explanation helps, but suffice to say your electrical check needs to include two things: check resistance per the manual within the component AND check those same conductors to ground.

 

[suprasvobodea]

I don't recall which terminal end goes to the valve, but the manual should tell you. Those << arrows in the diagram you posted tell you which gender the terminals are on each side. You want the measure the valve side. I think you can also see the wire runs. One end goes into the cab, the other runs up along the exterior underside. Yes, i can see that run along the frame... it goes to the control valve !

You need to measure from your wire in question to ground (any ground - could be a white/black wire in the harness or the actual vehicle frame or any bolt attached to it). I guess you're concerned about Black - Orange on pin 9 and Black - Red on pin 7. Yes, those are the 2 wires that go to the REAR Lift and Gate valves. If i do that , i should have Infinity .. ( NO GROUND ) and the meter should not register. If it Does.,,, thats the problem!! Nove of those wires should show a resistance value, but i am only checking the Rear Lift and gate valves

One of the more common failures is the insulation rubbing raw on the frame. That will produce a short to ground before it fails "open circuit". Meaning, until the wire rubs itself apart completely, you can pass a resistance check, but when the ECU tries to actually send an electrical signal (like the signal to open a valve) the electrical power needed to move the valve/solenoid leaks out of the conductor into the frame. Understand !

Not sure if that electrical explanation helps, but suffice to say your electrical check needs to include two things: check resistance per the manual within the component AND check those same conductors to ground. THANIK YOU ! - that is Very clear and i undcerstand

BTW- TO reply to INDOCRUISE questions, about the exact impedance values for the connector runs ( see photo below) , I will report them Here , and maybe back in Indocruise post earlier.

From the control valve assy >>>> to the ECU ( thru all 4 connectors)

SLRL = 12.6 ohm *( THIS IS MUCH HIGHER THAN THE REST AND THE ONE SOLENOID THAT IS NOT WORKING on the control valve assy.!) What's your take on this..?
SLGL = 1.2 ohm
SLFG = 1.2 ohm
SLFL = 3.3 ohm
H+ = 1.8 ohm ( this is the positive V from the source @ Pin #24 on the ACH connector )


<<RESPONSE>> SupraRX
See answers in BLUE

 

[suprasvobodea]

Firstly, as a base-line, what actual readings in ohms did you get when doing FSM test procedure directly between terminal 2 and each of the other four terminals at the Control Valve Assembly? The resistance from #2 to 1,3,4,5 were all 0.2 ohms on the control valve switch itself. The reading from the 5 pin Control valve connector are as follows:

From the control valve assy >>>> to the ECU ( thru all 4 connectors)

SLRL = 12.6 ohmn *( THIS IS MUCH HIGHER THAN THE REST AND THE ONE SOLNOID THAT IS NOT WORKING!) What's your take on this..?
SLGL = 1.2 ohm
SLFG = 1.2 ohm
SLFL = 3.3 ohm
H+ = 1.8 ( this is from #2 pin on Contorl valve assy connector >> to the positive V from the source @ Pin #24 on the ACH connector)

Secondly, when applying power directly to terminal 2 and terminal 5 of the Control Valve Assembly, the connector is (or should be) removed and the Control Valve Assembly is electronically isolated -- so neither the ignition nor engine need to be "ON". The purpose in this 'workaround' is ONLY to apply Pump pressure (by direct 12 volt connection to the AHC Pump) THROUGH the Levelling Valve (which has been opened by direct connection) to the 'shock absorbers' to raise the Rear of the vehicle AND ALSO to provide an opportunity to clear the hydraulic line by opening a Rear bleeder valve. First , i applied 12V to the Rear Lift valve (SLRL ) pin on the control valve body , and i could hear it activate, but the FRONT started falling , which i thought was strange (not the rear) so i stopped. I then applied 12 V directs to the pump and 12V to the SLRL again, but it did not move. But the leads from the battery to the pump almost melted! They were so HOT that one end of the 2 ft lead melted off ! I also could hear the pump straining hard , to pump which is what i would expect it to do. I quickly disconnected the leads and repaired that melted end.

Firstly, as a base-line, what actual readings in ohms did you get when doing FSM test procedure directly between terminal 2 and each of the other four terminals at the Control Valve Assembly?

Secondly, when applying power directly to terminal 2 and terminal 5 of the Control Valve Assembly, the connector is (or should be) removed and the Control Valve Assembly is electronically isolated -- so neither the ignition nor engine need to be "ON". The purpose in this 'workaround' is ONLY to apply Pump pressure (by direct 12 volt connection to the AHC Pump) THROUGH the Levelling Valve (which has been opened by direct connection) to the 'shock absorbers' to raise the Rear of the vehicle AND ALSO to provide an opportunity to clear the hydraulic line by opening a Rear bleeder valve.

The AHC system is NOT active in this 'workaround'.

NOTE: The Height Control Accumulator is not activated in this 'workaround' -- the solenoid valve remains closed and fluid flows directly to the Control Valve Assembly. Fluid passes through the Levelling Valves in the Control Valve Assembly if the "normally closed" Levelling Valves actually are open. The Gate Valves in the Control Valve Assembly are "normally open" when the vehicle is at rest.

The point of the 'workaround' is to get the vehicle raised so that efforts of bleeding air can begin PROVIDED THAT any electrical discontinuities or short circuits first have been discovered and resolved.

View attachment 3688730

The AHC system is NOT active in this 'workaround'.

NOTE: The Height Control Accumulator is not activated in this 'workaround' -- the solenoid valve remains closed and fluid flows directly to the Control Valve Assembly. Fluid passes through the Levelling Valves in the Control Valve Assembly if the "normally closed" Levelling Valves actually are open. The Gate Valves in the Control Valve Assembly are "normally open" when the vehicle is at rest.

The point of the 'workaround' is to get the vehicle raised so that efforts of bleeding air can begin PROVIDED THAT any electrical discontinuities or short circuits first have been discovered and resolved.

View attachment 3688730

Response for INDOCRUISE - In BLUE above

 

[suprarx7nut]

BTW- TO reply to INDOCRUISE questions, about the exact impedance values for the connector runs ( see photo below) , I will report them Here , and maybe back in Indocruise post earlier.

View attachment 3689507

From the control valve assy >>>> to the ECU ( thru all 4 connectors)

SLRL = 12.6 ohm *( THIS IS MUCH HIGHER THAN THE REST AND THE ONE SOLENOID THAT IS NOT WORKING on the control valve assy.!) What's your take on this..?
SLGL = 1.2 ohm
SLFG = 1.2 ohm
SLFL = 3.3 ohm
H+ = 1.8 ohm ( this is the positive V from the source @ Pin #24 on the ACH connector )


<<RESPONSE>> SupraRX
See answers in BLUE

You're measuring to the AHC ECU? The one tucked way up in the dash? And you're measuring this with both ends unplugged? If so, kudos. That's a ton of work, lol. I avoid that at all costs.

If that's how you're measuring it and you're getting 12.6 on that one leg, it's probably worth further investigation. First though, check for short to ground. Perhaps that's a nearly open circuit that's rubbing against the frame and getting a partial and intermittent connection. If it's a short to ground, check if the short is upstream or downstream of BI1 (it's almost always downstream). If you have a short downstream, then wire yourself a new conductor (we can link you to terminals, extractor and crimpers if needed) from BI1 to the valve. A few zip ties, a crimper, some terminals and loom if you're feeling ambitious and you might have it fixed.

 

[suprasvobodea]

You're measuring to the AHC ECU? The one tucked way up in the dash? And you're measuring this with both ends unplugged? If so, kudos. That's a ton of work, lol. I avoid that at all costs. Yes, both unplugged! . that ECU is tucked up by the steering wheel RH side. Its actually not that bad. Just need to remove the facia under the wheel, and 4 10mm bolts that hold the steel plate under the steering wheel. The ECU is right there!

If that's how you're measuring it and you're getting 12.6 on that one leg, it's probably worth further investigation. First though, check for short to ground. Perhaps that's a nearly open circuit that's rubbing against the frame and getting a partial and intermittent connection. If it's a short to ground, check if the short is upstream or downstream of BI1 (it's almost always downstream). If you have a short downstream, then wire yourself a new conductor (we can link you to terminals, extractor and crimpers if needed) from BI1 to the valve. A few zip ties, a crimper, some terminals and loom if you're feeling ambitious and you might have it fixed. I unplugged Bl1 back by the rear LH bumper and did a "short to ground test " per your recommendation. I tested all for lead from the Control Valve asy. NONE OF THEM REGISTERED! They are all OPEN !

But have I even BETTER NEWS that I will share with everyone the details and pictures of the success I just achieved yesterday!!!!!!!!!!!!!!!!! I FINALLY GOT MY LX TO PUMP OIL AND NOT SHOW THE 1762 CODE! It WORKS again! ( I do not think it was ever an electrical issue.- The LX has never been based up north - just Texas!) In Jan this year, started this journey by replacing the accumulator due to a sheared-off BLEEDER valve, which resulted in a rolled brake fitting that attached the SS line to the accumulator, and I removed the long L-shaped SS tube from the pump! I don't have any more time to describe this journey here, but I promise I will share pictures and the storyline later! All that matters is the PERSISTANCE AND PERSEVERANCE PAYS OFF!
** Response** - See BLUE text

 

[suprarx7nut]

But have I even BETTER NEWS that I will share with everyone the details and pictures of the success I just achieved yesterday!!!!!!!!!!!!!!!!! I FINALLY GOT MY LX TO PUMP OIL AND NOT SHOW THE 1762 CODE! It WORKS again! ( I do not think it was ever an electrical issue.- The LX has never been based up north - just Texas!) In Jan this year, started this journey by replacing the accumulator due to a sheared-off BLEEDER valve, which resulted in a rolled brake fitting that attached the SS line to the accumulator, and I removed the long L-shaped SS tube from the pump! I don't have any more time to describe this journey here, but I promise I will share pictures and the storyline later! All that matters is the PERSISTANCE AND PERSEVERANCE PAYS OFF!
** Response** - See BLUE text

Great news! Hell of a cliffhanger though... Can't wait to hear how you got it tackled!

 

[suprarx7nut]

@suprasvobodea Any update? Don't want you to forget the journey before you post up the details!

 

[suprasvobodea]

@suprasvobodea Any update? Don't want you to forget the journey before you post up the details!

Suprarxnut

YES! I will write up a FULL DOCUMENTARY later, I don't have the time right now. I think the majority of the problem ( the reason for 2 Pressure switches, Two new pumps ) was because it wasn't pumping oil, was the damn RETRUN Valve was plugged.! It was never the wiring or anything else. I'll describe more details and pictures of the return valve removal when I have more time

 

[IndroCruise]

Suprarxnut

YES! I will write up a FULL DOCUMENTARY later, I don't have the time right now. I think the majority of the problem ( the reason for 2 Pressure switches, Two new pumps ) was because it wasn't pumping oil, was the damn RETRUN Valve was plugged.! It was never the wiring or anything else. I'll describe more details and pictures of the return valve removal when I have more time

Looking forward to the full story ....

Meanwhile, for others coming this way, perusal of Posts #132, #139, #140, #141, #143, #145 which included diagrams, pictures and a video, all concerning the Return Valve, and which may be helpful. The blockage at the Return Valve is rare, or at least rarely reported, but may be a condition that is experienced in older vehicles, especially where there has been a lack of 'hydraulic hygiene' resulting in aged, sludgy AHC Fluid trapped in and around around the AHC system and not remediated by AHC Fluid change-outs at least as often as recommended in the Owners Manual for these vehicles -- 60,000 miles/6 years if I recall correctly -- or preferably twice as often as recommended long ago by @PADDO .

 

[Moridinbg]

Cleaned my return valve yesterday. It's no big deal, really. The Russian guy video shows everything important. As for the talking - nothing particularly interesting. He explains the steps and gives brief explanations how it all works together.
Mine was relatively clean with some minor residue.

 

[medtro]

-- clear the DTC,
-- press UP switch with furthest bleeder open (driver side rear),
-- bleed,
-- receive DTC C1762,
-- clear the DTC,
-- press UP switch with furthest bleeder open (driver side rear),
-- bleed,
-- receive DTC C1762,
-- clear the DTC,
-- press UP switch with furthest bleeder open (driver side rear),
-- bleed,
-- receive DTC C1762,
-- clear the DTC,

C1762 victim here trying to follow the steps listed above. Should the bleeder left open until the last step of "clear the DTC"? If not, when to close the bleeder?

 

[LX470YYC]

C1762 victim here trying to follow the steps listed above. Should the bleeder left open until the last step of "clear the DTC"? If not, when to close the bleeder?

Hi @medtro. Sounds like we're in the same boat at the same time. My understanding of the repeat bleed is to leave the bleeder open until the last step. Here's my ongoing thread if it can be of any help.

AHC pump assembly - bench test NG

Hello All. Currently trying to diagnose a persistent DTC1762 on my 2003 LX470. Lots of diagnostic history I can share at some point, but right now I'd like to see if anyone has any input specifically on getting flow from the pump assembly. I've pulled the pump assembly and have bench tested it...

forum.ih8mud.com

 

[ClassyJalopy]

Cleaned my return valve yesterday. It's no big deal, really. The Russian guy video shows everything important. As for the talking - nothing particularly interesting. He explains the steps and gives brief explanations how it all works together.
Mine was relatively clean with some minor residue.

Cograts! Which "Russian Guy" video are you referring to?