Fix for ABS, VSC TRAC, VSC OFF, & Brake lights remain on no CEL, or how to repair an ECU (2 Viewers)

[Slashzero]

You probably have the same issue I have.

View attachment 2389081

Thanks! I still can’t find my scan tool, so I took it down the street to my local mechanic (who happens to be replacing the water pump on my Tiguan, currently... man that is a huge pain in the ass, thanks Volkswagen).

Anyway, in my case it turned out to be an O2 sensor, opposite side of the one replaced last year. I went ahead and asked him to order a new sensor and take care of it. Don’t want to deal with wrenching in this heat.

 

[ramangain]

Don’t want to deal with wrenching in this heat.

It's a helluva weight loss regimen for us portlier folks though!

 

[rrc swb]

Thanks! I still can’t find my scan tool, so I took it down the street to my local mechanic (who happens to be replacing the water pump on my Tiguan, currently... man that is a huge pain in the ass, thanks Volkswagen).

Anyway, in my case it turned out to be an O2 sensor, opposite side of the one replaced last year. I went ahead and asked him to order a new sensor and take care of it. Don’t want to deal with wrenching in this heat.

Glad to see that they found the issue.

My scanner won't read any codes... I don't have the CEL on.

 

[FJRyder]

My scanner won't read any codes... I don't have the CEL on.

That's the key for this specific issue. No CEL since the problem is independent from other systems. Think about it this way, since this TRAC/ABS ECU can't communicate, the other ECUs don't know there is a problem.
Next step probably should be to scan the ECUs with Techstream and see if you get a response from TRAC/ABS ECU.

 

[Ninja Cruiser100]

You also have to have a scanner that will read ABS codes.

 

[FJRyder]

You also have to have a scanner that will read ABS codes.

To use Techstream, yes. But the thing that really confused me was when I ran through the self diagnostics the manual way, I was getting codes that didn't make sense (ACH was sending codes through the flashing light, not the TRAC/ABS computer), or basically no codes like everything was OK. So I think if you run through the diagnostics (which costs nothing but time) and get the same strange response, its likely the same issue. BTW, the Techstream cable off of Amazon is only $20-30, so not too painful.

what I found was that it definitely has to be soldered exactly as shown due to being smaller it is the only way it will reach across the three contacts

I spent a little time looking for the correct size. So far no luck, but there has to be one out there.

 

[dgz32]

Big thanks for posting this repair, FJRyder. I'll be attempting this in the next few days once my order comes in.

 

[Y-SC]

Big thanks, FJRyder. My 2002 lx470 has exactly the same symptoms - all four lights on, DLC diagnosis suggest no connection to ABS module (the four lights not blinking but ACH light blinks). Took the module off and opened it up, and will attempt the repair soon. One question, how do you take off the x3 resonator, just pry it off with a small flathead screwdriver? Thanks!

 

[FJRyder]

One question, how do you take off the x3 resonator, just pry it off with a small flathead screwdriver? Thanks!

NOOOOOOOO!!!!!!!

If you pry it off you will break the traces on the PCB.

You must use a soldering iron to remove the resonator. Since it sounds like you never worked on electronics, I suggest you find someone that knows how or you could turn it into a complete ECM replacement. Look back near the beginning of my post. I suggest a couple places that could do the repair for you for $250.

Worst case, I could do it for you (for some small reward, hint I like beer). But I'm out of town next week.

 

[icce]

Update on mine... shop can’t find someone to do board level repair. Any electrical gurus out there that can help? I have a replacement board on order just in case but hoping for the cheaper fix.

 

[FJRyder]

Update on mine... shop can’t find someone to do board level repair. Any electrical gurus out there that can help? I have a replacement board on order just in case but hoping for the cheaper fix.

I wasn't intending to get into the repair business, but for a small token of gratitude (i.e. beer) I can do this. I'm out of town next week and it would be done at my earliest convenience.

 

[icce]

where are you located?

 

[FJRyder]

where are you located?

Phoenix

But you can always mail it.

 

[Primedtsi]

New guy here with the exact issue in my 02 4runner. Same issue and resonator bad. FJRyder I messaged you about sending my ecu to you for repair.

 

[FJRyder]

Big thanks for posting this repair, FJRyder. I'll be attempting this in the next few days once my order comes in.

Any luck with your repair?

 

[dgz32]

Any luck with your repair?

So this is funny. I pulled the unit to look at it before my parts and soldering stuff arrived. Opened it up—all that. Then had to drive somewhere—so reinstalled it real quick. No lights. And they've not come back with daily driving since. So I'm presuming that it was a loose connection at the unit itself. Either that or it's decided to live a little longer. Either way, I'm now set up with everything to do the repair if/when it does happen again.

 

[Primedtsi]

Huge thanks to FJRyder for repairing my ABS computer. My 2002 4Runner experienced the exact same issues (dash lights galore, dead communication with ABS module, p0500 code in ECU, dead speedometer/odometer). I was able to follow his instructions in this thread and pinpoint my issue to the same reducer. Part # for my 4runner module is 89540-35270. Ordered a reducer from Digikey, then sent the module with it to him. Super quick turn-around and fixed my issue. It's surprising how hard it was to find someone locally in my area that has the skill to repair a circuit board!

FYI vehicle is still "driveable" without the computer installed. You have basically manual brakes, dead speedometer, and the odometer does not register but the transmission still shifts fine. Also, the 4runner module does not interchange with the LX470 model.

 

[RootMeanSqr]

FYI vehicle is still "driveable" without the computer installed. You have basically manual brakes, dead speedometer, and the odometer does not register but the transmission still shifts fine. Also, the 4runner module does not interchange with the LX470 model.

When I had my brake module out of the vehicle to repair it, I thought my brakes worked too, until they didn't. You've got about 35-40 presses of the peddle before the peddle goes to the floor with no brakes. I would not expect to drive it without the the brake module.

 

[icce]

Replaced my ABS ECU today and the issue was resolved. I was able to locate a replacement part from overseas and did the swap myself. I will be sending my original one out to @FJRyder for repair and will keep the replacement part as a spare in case of future failures. Nice to have a clear cluster again!

 

[icce]

Not sure what happened with the photos, they are definitely not oriented like that on my computer. Anyone know how to fix that?