ABS System not communicating with code reader (1 Viewer)

[K5Guy]

Does anyone know what might cause a code reader to not be able to detect/ communicate with the ABS system? I have every brake light that can be on on currently and when I tried to find a code for it the reader can not detect my ABS system. I have a 2000 LX470.

I am leaning towards the ABS control module but I am hoping there may just be a relay or something much cheaper.

thanks,

 

[2001LC]

Most readers recognize the vehicle, VIN, yr, make & model. Some require (more so in pre 03) to input that info. Make sure it's recognized by reader, if so try different reader.

Also make sure fluid not low. Read directions for topping on reservoir.

 

[K5Guy]

Most readers recognize the vehicle, VIN, yr, make & model. Some require (more so in pre 03) to input that info. Make sure it's recognized by reader, if so try different reader.

Also make sure fluid not low. Read directions for topping on reservoir.

I have tried 2 different readers. last one was a Snapon at a shop near house. used vin vehicle info still nothing. fluid is at max level.

 

[RootMeanSqr]

Jumper the Tc and E1 on the Diagnostic terminal and turn the key to On. ABS light should flash codes, or the All OK code if none. If ABS light doesn't flash at all, ABS ECU is dead. This happened to me, but was able to revive by replacing the ceramic resonator on the board. There's a thread on here about that.

 

[2001LC]

In addition to @RootMeanSqr suggestion. Make sure the OBD port is reading at least other systems like live engine data.

 

[K5Guy]

In addition to @RootMeanSqr suggestion. Make sure the OBD port is reading at least other systems like live engine data.

it picked up the bad o2 sensor I have at the moment as well as all the other systems on the vehicle just no ABS.

 

[K5Guy]

Jumper the Tc and E1 on the Diagnostic terminal and turn the key to On. ABS light should flash codes, or the All OK code if none. If ABS light doesn't flash at all, ABS ECU is dead. This happened to me, but was able to revive by replacing the ceramic resonator on the board. There's a thread on here about that.

can you explain that a bit more, it was a little over my head. Are you talking about using a wire to jump form one pin to the other on the OBD plug in?

 

[2001LC]

I'd get O2 squared away first. These ABS systems shut down if engine has any DTC set off. Even disconnecting the MAF will shut down ABS. Although you should be able to read at least 1 brake code (DTC), either active or pending. BTW: Tech stream is more revealing than these code reads.

If brakes work okay, no alarm and booster motor run time test of 30 to 40 seconds all good. Also check if the brake warning alarm sound off, by rapidly and continuously pumping brake pedal with IG switched to ON. Then if all that checks out as good, I'd put ABS lack of DTC visible in code reader, on back burner for now.
Run time spec 30 to 40 seconds,

 

[K5Guy]

I'd get O2 squared away first. These ABS systems shut down if engine has any DTC set off. Even disconnecting the MAF will shut down ABS. Although you should be able to read at least 1 brake code (DTC), either active or pending. BTW: Tech stream is more revealing than these code reads.

If brakes work okay, no alarm and booster motor run time test of 30 to 40 seconds all good. Also check if the brake warning alarm sound off, by rapidly and continuously pumping brake pedal with IG switched to ON. Then if all that checks out as good, I'd put ABS lack of DTC visible in code reader, on back burner for now.
Run time spec 30 to 40 seconds,
View attachment 2140848

thank you for the help. I did not realize the O2 sensor could interfere with the ABS, good to know. I will get that squared away and try the steps above. and brakes work fine currently, other than the actual ABS function when braking hard.

 

[2001LC]

ABS & VSC is over rated anyway.

But do all the brake test I outline before driving, just to be safe.

 

[K5Guy]

I'd get O2 squared away first. These ABS systems shut down if engine has any DTC set off. Even disconnecting the MAF will shut down ABS. Although you should be able to read at least 1 brake code (DTC), either active or pending. BTW: Tech stream is more revealing than these code reads.

If brakes work okay, no alarm and booster motor run time test of 30 to 40 seconds all good. Also check if the brake warning alarm sound off, by rapidly and continuously pumping brake pedal with IG switched to ON. Then if all that checks out as good, I'd put ABS lack of DTC visible in code reader, on back burner for now.
Run time spec 30 to 40 seconds,
View attachment 2140848

so i checked the pump it stops correctly but I did not get any alarm when i presses the pedal a bunch. does that mean the CEL for the O2 sensor might still be the problem?

 

[2001LC]

It means alarm not working. Why is unknown. But likely the ABS EUC has connection issue or bad. I would not be comfortable driving if alarm not working. If pressure dropped or lost, due to booster motor failure or fluid loss. You would not know it, as dash is already indication ABS issue. You must stop diving this rig.

ABS issue will not sets off a O2 DTC (code). The O2 is a separate issue.

Most any issue that effects engine or voltage will shut down ABS as a safety.

You can drive with O2 issue, but not a brake issue.

If you want to fix ABS issue first, go ahead. But as long as the engine DTC keeps coming up, your ABS system will shut down. That's why I like getting other DTC corrected first. I've never had a transmission DTC, but likely ABS would shut down with one of those also. Even low low voltage, and ABS DTC pops up.

 

[K5Guy]

It means alarm not working. Why is unknown. But likely the ABS EUC has connection issue or bad. I would not be comfortable driving if alarm not working. If pressure dropped or lost, due to booster motor failure or fluid loss. You would not know it, as dash is already indication ABS issue. You must stop diving this rig.

ABS issue will not sets off a O2 DTC (code). The O2 is a separate issue.

Most any issue that effects engine or voltage will shut down ABS as a safety.

You can drive with O2 issue, but not a brake issue.

If you want to fix ABS issue first, go ahead. But as long as the engine DTC keeps coming up, your ABS system will shut down. That's why I like getting other DTC corrected first. I've never had a transmission DTC, but likely ABS would shut down with one of those also. Even low low voltage, and ABS DTC pops up.

That is what I was originally thinking was the problem. The ECU is on the side of the Booster correct? is there a way to repair? Thanks again for your help.

 

[Hugh Heifer]

There are quite a few OBDII readers that will only give engine related codes and not ID your nonengine codes. Although I am a little surprised the Snap On one didn't.... a little.

 

[gatormark91]

Techstream will show you everything.

 

[Hugh Heifer]

Techstream will show you everything.

Fully aware. Some of us do not have that tech however.

 

[2001LC]

That is what I was originally thinking was the problem. The ECU is on the side of the Booster correct? is there a way to repair? Thanks again for your help.

No, see ECU below
You'll need to check with @RootMeanSqr. But I believe he's saying jump at the DLC3, and this ABS & BA & TRAC & VSC ECU. I see the Buzzer is there also. I'd inspect the wire harness on ECU first thing.