3FE ECU-AFM question (1 Viewer)

[red66toy]

Hello everyone.
So I have been chasing a weird idling issue. I was getting a code 22 (water temp sensor short) so I thought I had located the problem. However the wiring and temp sensor check out. which made me suspect the ECU. So I proceeded to do the ECU test in the FSM. I found a potential issue and have some questions.
Here are the volt readings from the AFM at the ECU connections:

So at the fully open setting, and at 3000 rpms, I am getting too high a volt readings by back probing at the ECU. Testing the resistance of the AFM terminals on the AFM itself all check out. Does this mean the ECU is the culprit? Or is the AFM dictating the voltages and that is bad?

 

[ToyotaMatt]

Did U follow / trace the coolant temp sensor wire's all the way through the fire wall , through the rubber boot ?


Toyota's Tend to liker to partial crack or fracture there and only say 1/2 or 75% of the copper strands wire break leaving the others intact , thus giving the ECU or Gauge sender in the cluster a week incorrect signal readout or input in your case

also , dont assume the female spade connector on the sender is good , assume its bad and put a fresh connector on it step #1

just like the fire wall it wiggles back and forth and breaks strands of copper wire after age and time ............

do a continuity test on the sensor wire all the way down to the ECU , that will also smoke out a broken or severed input wire

the wire cracking at the firewall boot will happen inside the insulation and be hidden from view

i have seen and repaired this same set of symptoms in several toyota 's of your era's in the past

 

[LAMBCRUSHER]

That^^^

 

[red66toy]

Did U follow / trace the coolant temp sensor wire's all the way through the fire wall , through the rubber boot ?


Toyota's Tend to liker to partial crack or fracture there and only say 1/2 or 75% of the copper strands wire break leaving the others intact , thus giving the ECU or Gauge sender in the cluster a week incorrect signal readout or input in your case

also , dont assume the female spade connector on the sender is good , assume its bad and put a fresh connector on it step #1

just like the fire wall it wiggles back and forth and breaks strands of copper wire after age and time ............

do a continuity test on the sensor wire all the way down to the ECU , that will also smoke out a broken or severed input wire

the wire cracking at the firewall boot will happen inside the insulation and be hidden from view

i have seen and repaired this same set of symptoms in several toyota 's of your era's in the past

Thank you for the thoughtful post. Its also a scary one! hahaha.
So I have had a lot of high idle/hesitation issues that (based on past mud threads) point directly to a bad temp sending unit. So I tested continuity both at the sensor and at the ECU. Same readings. I tested the continuity of the wires and they check out good. Checked cross continuity to check for a short. No contact. The wires also don't have continuity to ground so no short out there as well. So it all passes based on the FSM. Female connector was replaced by the PO at some point. Seems solid. That made me suspect the ECU.

However the idling issues were at first sporadic and have been getting more frequent and the symptoms more extreme (died at a stoplight and was hard to restart). So maybe it is a deep break getting worse. I am not sure how best to get at those wires as they are so buried .

 

[ToyotaMatt]

sorry if i missed it , But did U replace the temp. sender & how much is the one U need at the dealer Toyota Genuine Part ?

 

[red66toy]

sorry if i missed it , But did U replace the temp. sender & how much is the one U need at the dealer Toyota Genuine Part ?

I haven't replaced the sensor. It's about $60 I think from Toyota

 

[ToyotaMatt]

have U tried jumping TE - E1 in the TCCS ECU connector under hood for a extended period of time to see if the symptoms persist ?

doing this procedure should be outlined in the factory RM vol 1 MFI section or EFI

 

[red66toy]

have U tried jumping TE - E1 in the TCCS ECU connector under hood for a extended period of time to see if the symptoms persist ?

doing this procedure should be outlined in the factory RM vol 1 MFI section or EFI

I have not and no idea what that procedure is beyond just checking for codes. I will go back to the FSM and look for it
Ok so I looked in the 3FE FSM. I didn't see a section about jumping those two ports for an extended period of time. All I see is checking timing by jumping those ports and checking engine codes. Does it put the computer into some sort of pre-programmed mode without input from outside sensors?

 

[red66toy]

@RAGINGMATT here are some pics of the connector. And actually the mystery deepens a little here.
Connector the PO added:

However I noticed something. Here is the temp sensor on my FJ62:
EFI temp sensor is the yellow one

However here is the Toyota (89422-12010) one:

Notice the difference in color and the ridge on the OEM one. My sensor does not have this ridge..... What the heck do I have?!

 

[89BIGBLUE]

Is it a sensor froam a later model 3FE?

 

[ToyotaMatt]

@RAGINGMATT here are some pics of the connector. And actually the mystery deepens a little here.
Connector the PO added:

However I noticed something. Here is the temp sensor on my FJ62:
EFI temp sensor is the yellow one

However here is the Toyota (89422-12010) one:

Notice the difference in color and the ridge on the OEM one. My sensor does not have this ridge..... What the heck do I have?!

what the " heck " U might have is just diagnosed the DTC or trouble code issue , By installing the correct sender that may lead to the fix

 

[red66toy]

Is it a sensor froam a later model 3FE?

Later 3FE temp sensor (89422-22010)

 

[red66toy]

what the " heck " U might have is just diagnosed the DTC or trouble code issue , By installing the correct sender that may lead to the fix

I hope so! Now I need the correct connector for it as well... anyone have one?
Correct sensor has now been ordred

 

[red66toy]

So looks like the temp sensor I have on there now is some generic one (Standard motor products) that is for the cruiser and the connector is a generic AC Delco connector.

 

[jmstu76]

Are you positive what you are calling a sensor isn't the thermo time switch? I have been chasing issues in my 62 as well I believe the sensor on the passenger side of the thermostat housing is the sensor that relays engine coolant temp to the ECU for EFI.

I also believe the sensor under your yellow generic unit with the single blue spade is the sender for the dash gauge.

 

[red66toy]

Are you positive what you are calling a sensor isn't the thermo time switch? I have been chasing issues in my 62 as well I believe the sensor on the passenger side of the thermostat housing is the sensor that relays engine coolant temp to the ECU for EFI.

I also believe the sensor under your yellow generic unit with the single blue spade is the sender for the dash gauge.

So the sensor on the passenger side top is the temp sensor for the fuel pressure circuit. The sensor on the top drivers side is the cold start injector temp sensor. The sensor below that is the EFI temp sensor for the ECU and the little sensor below/next to that is the gauge temp sensor. Lots of temp sensors!! When a code 22 pops up it is in reference to the EFI temp sensor.

 

[red66toy]

New OEM sensor installed with a good used OEM connector (HUGE thanks to @pappy ).

Ran great on its first test drive around the city. No weird idle at all. Just right! Thanks to all for the help!

 

[jmstu76]

Did U follow / trace the coolant temp sensor wire's all the way through the fire wall , through the rubber boot ?


Toyota's Tend to liker to partial crack or fracture there and only say 1/2 or 75% of the copper strands wire break leaving the others intact , thus giving the ECU or Gauge sender in the cluster a week incorrect signal readout or input in your case

also , dont assume the female spade connector on the sender is good , assume its bad and put a fresh connector on it step #1

just like the fire wall it wiggles back and forth and breaks strands of copper wire after age and time ............

do a continuity test on the sensor wire all the way down to the ECU , that will also smoke out a broken or severed input wire

the wire cracking at the firewall boot will happen inside the insulation and be hidden from view

i have seen and repaired this same set of symptoms in several toyota 's of your era's in the past

SO I've been having intermittent good and poor running condition. I read what you posted above and it got me thinking. Tonight while filling up I grabbed the FI harness between the No. 6 and the firewall and moved it up and down about an inch and the engine immediately died. It started back up and then it died as I was pulling away from the pump. I popped the hood, moved the harness again and it fired up. It brought me home but again wasn't running on all 6.

Sounds like a broken wire in the harness to me.....anyone else?

 

[LAMBCRUSHER]

Easily could be