1997 LC - Shift Solenoid P0753 (1 Viewer)

[rowfour]

hello.

new to 80 series. Just picked up a 97 Collectors Edition 220,000 mi.

it was running good for about 400 miles before I decided to clean the interior. I pulled the carpet and center console out. Unplugged and reconnected everything back. It ran for maybe 100 miles then it threw a code P0753. Truck didn’t seem to have 1st gear - no power but then picks up.

I probed for resistance but didn’t find a short from both the ECM and trans connector.
I manually shifted L-2-D and shifted fine.
Trans fluid not dirty and level’s good.
Cleared code but came back.
Tested the 2ND start and it started okay.

my question before I drop the pan and replace solenoids is, would there be anything in the center console that could cause this?

thanks in advance.

 

[yknot123]

hello.

new to 80 series. Just picked up a 97 Collectors Edition 220,000 mi.

it was running good for about 400 miles before I decided to clean the interior. I pulled the carpet and center console out. Unplugged and reconnected everything back. It ran for maybe 100 miles then it threw a code P0753. Truck didn’t seem to have 1st gear - no power but then picks up.

I probed for resistance but didn’t find a short from both the ECM and trans connector.
I manually shifted L-2-D and shifted fine.
Trans fluid not dirty and level’s good.
Cleared code but came back.
Tested the 2ND start and it started okay.

my question before I drop the pan and replace solenoids is, would there be anything in the center console that could cause this?

thanks in advance.

View attachment 2656965

Welcome to i8hmud.
Not skilled with the electrical connections in this area that could effect the transmission. Have seen many forums on this transmission.
We have had similar code 750 Solenoid A mech has said that they see this last long time and some they replace all solenoids.
Was gonna drop pan like you but decided to do a little work after ordering one solenoid Ca CHING.
Why put new solenoid in with old transmission fluid?
Drained one gallon from drain plug? About what will drain but not even close to total amount.
This cancelled the Engine code light. Yes the tranny worked a little better.
Researched forums and found one that showed how to power flush the tranny by using its own power.
Pumped about 11 gallons into the system and back out the oil cooler.
Watching the fluid change from brown to red pretty satisfyingly.
Immediately the tranny drove and shifted like never before. Did another quick flush recently after Engine light came back Code 750.
Cleared code and adjusted the fluid level WHEN HOT read FSM

The 80 shifts now and runs like it never has before, even burning oil.

Side note. If you are still this far along, it would be worth your time to clean out the rear blower motor for heat, Lots of stuff gets into the plastic spinning fan and get stuck.
yknot

 

[rowfour]

Not skilled with the electrical connections in this area that could effect the transmission. Have seen many forums on this transmission.
We have had similar code 750 Solenoid A mech has said that they see this last long time and some they replace all solenoids.
Was gonna drop pan like you but decided to do a little work after ordering one solenoid Ca CHING.
Why put new solenoid in with old transmission fluid?
Drained one gallon from drain plug? About what will drain but not even close to total amount.
This cancelled the Engine code light. Yes the tranny worked a little better.
Researched forums and found one that showed how to power flush the tranny by using its own power.
Pumped about 11 gallons into the system and back out the oil cooler.
Watching the fluid change from brown to red pretty satisfyingly.
Immediately the tranny drove and shifted like never before. Did another quick flush recently after Engine light came back Code 750.
Cleared code and adjusted the fluid level WHEN HOT read FSM

The 80 shifts now and runs like it never has before, even burning oil.

Side note. If you are still this far along, it would be worth your time to clean out the rear blower motor for heat, Lots of stuff gets into the plastic spinning fan and get stuck.
yknot

Hey.

so to clarify, you didn’t replace any solenoids and just did a fluid flush?

at the moment, the ATF is still red and clean - at least from what the dip stick shows.

thanks again.

 

[yknot123]

Hey.

so to clarify, you didn’t replace any solenoids and just did a fluid flush?

at the moment, the ATF is still red and clean - at least from what the dip stick shows.

thanks again.

Good Day,
Yes did a power fluid flush.
I purchased 1 solenoid Expensive Need 3 solenoid
Did not install new solenoid.
Many different views or perspectives on the A343F Transmission solenoid issue and techniques for changing fluid.
The transmission fluid does not really drain out like motor oil. Most of the Tranny fluid stays in the system when drained.
This is where the power flush comes in. Dealer has a machine that pumps fluid through system.
I8hmud members have come up many clever systems.
After reviewing many forums we used this technique.
Remove front grill to access oil cooler. Have 5/8"? clear hose, couple of drain bottles, pliers, Phillip's, long skinny funnel for dipstick etc
Run clear tube up to top This is your drain line for the end of the system and old fluid removal.
I used a hand pump attached to the OEM tranny line back to transmission for new fluid. This sorta worked but found a gravity feed also worked my second time.
Install drop clothes to trany dipstick to protect wires etc.
Install funnel, long and skinny like me.. I used two funnels to help with angle and allow air into filling.
TRANSMISSION NEEDS TO HAVE FLUID AT ALL TIMES
Patience is key to most 80 repairs including pouring Tranny fluid SLOWWWWW
I added about a gallon or less to overfill tranny.
Luckily my daughter and wife can help.
Daughter in driver seat, wife with the pump and me with the dipstick funnel.
Start truck with EBRAKE and FOOT on brake.
Run Through the tranny gears as the old fluid comes out and as you pour /pump more new fluid.
May need to stop engine to add more tranny fluid as it pumps faster than you can add. Judge amount pumped out with the amount poured back in.
We ran about 12 quarts through our tranny. Until red and clean.
Reinstall and check fluid on level surface after running for 20 -30 minutes through all the gears.

Our cruiser is at 300k and needed a good BASELINE for all fluids.
Time goes by fast and even being a owner ,since 2003 for ours, some things just slip by. IE TRANNY fluid change.
Baselining the 80 was the best thing for the way it runs, besides redoing the head gasket, and all hoses.
Take care and enjoy


Side notes.
The new transmission fluid will at some point become frothy from air. You will see it in clear tube drain line.
Turn engine off. BE Patient and let everything settle down.
This is from not being able to pour as much as the pump ejects. PATIENTS will help with this in the process of not pumping out more than refilling.
Yknot

 

[CJK]

Hey, I had this issue and spent >$1K chasing it.

My issue was that the solenoid wiring between Trans and ECU had rubbed on the body and frayed. That wiring is on top of the transmission so hard to see from under the vehicle — removing the front passenger fender provides for "better" access.

When tested, The wire showed continuity but the resistance was so high that the ECU kept the truck in Limp mode

Lexus LX450 - Transmission - Shift Solenoid Electrical Code

Hi all, Long-time Lurker, finally running into an issue I haven't been able to solve either on my own or with the help of the "Search" button on the forum. I have a stock Lexus LX450 with 176K miles. I recently added a center diff switch and performed the 7-pin mod, as well as replaced the...

forum.ih8mud.com

 

[yknot123]

Hey, I had this issue and spent >$1K chasing it.

My issue was that the solenoid wiring between Trans and ECU had rubbed on the body and frayed. That wiring is on top of the transmission so hard to see from under the vehicle — removing the front passenger fender provides for "better" access.

When tested, The wire showed continuity but the resistance was so high that the ECU kept the truck in Limp mode

Lexus LX450 - Transmission - Shift Solenoid Electrical Code

Hi all, Long-time Lurker, finally running into an issue I haven't been able to solve either on my own or with the help of the "Search" button on the forum. I have a stock Lexus LX450 with 176K miles. I recently added a center diff switch and performed the 7-pin mod, as well as replaced the...

forum.ih8mud.com

Thanks for the forum on issue. Never had the skills for all those electrical tests myself.
I can attest to the importance of good wiring. The main wiring harness needs to be disconnected from transmission in order to do the "DREADED HEADGASKET"
I also chased the wires at harness connection again after head gasekt. Did find some flawed wires. So replaced a section with new harness pins.
Am I not convinced this was or could still be our challenge. code 750 Solenoid A

The flush of the transmission and cooler seemed to do more than anything. Along with being at the right fluid level when hot.
Glad to see that this problem can be just about anything,


Sorry it took so much energy.
Will defiantly look at this wire location next time our CEL 750 Code Solenoid A appears

 

[rowfour]

Hey, I had this issue and spent >$1K chasing it.

My issue was that the solenoid wiring between Trans and ECU had rubbed on the body and frayed. That wiring is on top of the transmission so hard to see from under the vehicle — removing the front passenger fender provides for "better" access.

When tested, The wire showed continuity but the resistance was so high that the ECU kept the truck in Limp mode

Lexus LX450 - Transmission - Shift Solenoid Electrical Code

Hi all, Long-time Lurker, finally running into an issue I haven't been able to solve either on my own or with the help of the "Search" button on the forum. I have a stock Lexus LX450 with 176K miles. I recently added a center diff switch and performed the 7-pin mod, as well as replaced the...

forum.ih8mud.com

Thanks for the heads up!

i’m about to start the work today for the solenoids - they’re not cheap.

i’ll double check the wiring. I hope that if it’s damaged that it will be obvious.

if i don’t see damage and probed okay. I’ll go for the solenoids. Or power flush then solenoids.

thanks again.

 

[rowfour]

Okay. So I poked around yesterday. Removed the center console cover, verified the PWR/2ND switch wiring, everything looked good. I probed the connector to the ECM again for S1 and S2, I got a reading of 14.8 ohms for S2 and nothing for S1.
Manual says ECM if either S1 or S2 read within specs.

if i can get some help confirming this, that would be amazing.

thanks.

 

[yknot123]

Good Day, What great work you are doing!
I know when my skills are not able to accomplish certain things. Electrical has always been a week point for me.
For me electrical work is making sure connections are easy and the wires not flawed coming to the plastic connections
Regarding your transmission electrically on exterior for us it was the connection from wireharness glove box to engine then tranny.
Located at L Drivers side rear well. I think 3 maybe only 2 plugged connections. Viewable from top sorta way back under fire wall. Easier to view and access with wheel removed and rubber inner wheel flair removed.

Reread the entire post from beginning.
Your first questions is where I would go back too.
Can it be something when I had interior apart. From the picture there are plugs disconnected. It maybe something as simple as the plug connection not being connected.
Toyota Plugs snap into place. No snap not right. On older 80.s the plugs are full of grit grim
Found that the cleaning and care of these plastic connections is about the most important detail on a Cruiser. No connection no go.
This is from the experience of not making connection properly myself. This lead to knowing more about the plastic clips than needed.

My fluid flush of tranny has certainly helped but will not solve a electrical issue. IE Solenoid, connection, flawed wires, bad ECM etc.
The tranny flush was a easy cheap thing to do for me. Part of baselining the 80 after 18 years of family trips and short kids sporting events.
Really think if my CEL does not come back on, luck would have it, that after many miles of clean fluid the Solenoids area working better.

I am going to check our kick down cable adjustment as noted in another post. You may want to too. Simple and no cost.
As you can see my theme is patience, cleaning, low initial cost, check basics, replace with OEM and never forget that it worked before I FIXED IT

 

[yknot123]

Good Day, What great work you are doing!
I know when my skills are not able to accomplish certain things. Electrical has always been a week point for me.
For me electrical work is making sure connections are easy and the wires not flawed coming to the plastic connections
Regarding your transmission electrically on exterior for us it was the connection from wireharness glove box to engine then tranny.
Located at L Drivers side rear well. I think 3 maybe only 2 plugged connections. Viewable from top sorta way back under fire wall. Easier to view and access with wheel removed and rubber inner wheel flair removed.

Reread the entire post from beginning.
Your first questions is where I would go back too.
Can it be something when I had interior apart. From the picture there are plugs disconnected. It maybe something as simple as the plug connection not being connected.
Toyota Plugs snap into place. No snap not right. On older 80.s the plugs are full of grit grim
Found that the cleaning and care of these plastic connections is about the most important detail on a Cruiser. No connection no go.
This is from the experience of not making connection properly myself. This lead to knowing more about the plastic clips than needed.

My fluid flush of tranny has certainly helped but will not solve a electrical issue. IE Solenoid, connection, flawed wires, bad ECM etc.
The tranny flush was a easy cheap thing to do for me. Part of baselining the 80 after 18 years of family trips and short kids sporting events.
Really think if my CEL does not come back on, luck would have it, that after many miles of clean fluid the Solenoids area working better.

I am going to check our kick down cable adjustment as noted in another post. You may want to too. Simple and no cost.
As you can see my theme is patience, cleaning, low initial cost, check basics, replace with OEM and never forget that it worked before I FIXED IT

Update our 97 A343F gave us the Code 750 Solenoid A
This has been going off and on for a while.
Lesson learned. Tranny needed to be flushed and does make a difference.
Did it solve solenoid problem. Does not appear that it has.
Purchasing the OEM solenoids, slowly, for replacement.

 

[rowfour]

Update our 97 A343F gave us the Code 750 Solenoid A
This has been going off and on for a while.
Lesson learned. Tranny needed to be flushed and does make a difference.
Did it solve solenoid problem. Does not appear that it has.
Purchasing the OEM solenoids, slowly, for replacement.

Hey there.

i’m now in the process of replacing the shift solenoids. Took it apart last night and reassembling today.

thanks

 

[rowfour]

So before I pulled the old shift solenoids, I probed them first.

S1 was warm. S2 and SL were normal (cold). I wonder if that meant that S1 has faulted internally????

i know I hope so..

 

[yknot123]

Why thanks for the pictures? What's your plan with Solenoids?

I have one solenoid and it is Solenoid A for us. Replace with one new Solenoid. Test, clean, and reinstall other 2 solenoids.
Kind of my plan instead of buying 2 more for around 450$
Have seen various sites, show how to test a solenoid. Probably even a older forum or resource on IH8MUD , as this is not a new challenge.
My mechanic says they do wear out. Think of it like a fuel injector, spraying or opening/closing millions of times.
S1 is used the most as it get us going.

 

[rowfour]

I’m replacing both when I get home. I’ve read that placing them in an ultrasonic cleaner might get them going again and blowing air to test if it actuates. Makes sense in theory but I don’t want to go the distance of starting over if they still fail after all that trouble - cleaning the gasket is not that enjoyable.

the OE solenoids that I got from Toyota are Denso vs AISIN (original) And somewhat different in build. Mounting bracket seem to match though.

i heard that Isuzus use the exact same solenoids and run about $200 for the set.

 

[yknot123]

I’m replacing both when I get home. I’ve read that placing them in an ultrasonic cleaner might get them going again and blowing air to test if it actuates. Makes sense in theory but I don’t want to go the distance of starting over if they still fail after all that trouble - cleaning the gasket is not that enjoyable.

the OE solenoids that I got from Toyota are Denso vs AISIN (original) And somewhat different in build. Mounting bracket seem to match though.

i heard that Isuzus use the exact same solenoids and run about $200 for the set.

View attachment 2674216

Great work. Are you going to replace all 3 solenoids. I too have heard that about Isuzu but have not been able to track part down for A343F.
Thanks for pointing out the gasket challenge. Main thing from me not putting up on stands for a day or so. Looks nice and clean now!

 

[rowfour]

I replaced just the two shift solenoids. Cleared the code. Test drove it tonight and MIL didn’t and hasn’t come back. Shifting smooth again. Other than cleaning gasket, the job wasn’t too bad.

thanks for the pointers!

 

[SpillmanCruiser]

What are the part numbers for the 1997 LC A343F Transmission solenoids? Can the Isuzu solenoids be used in the A343F?