ABS ECU Diagnostcs/Replacement

[ds307]

I have a 1998 Carmy, ABS light on.
I removed shorting pin and installed jumper to read codes on ABS light.

The light is on solid, indicating ECU problem.

What other diagnostics can I perform to determine if the ABS ECU needs to be replaced?

Is the ABS pump integrated with the ECU? Thoughts on replacement?

Also, how do you remove the large wiring harness connector from the top/side of the ABS unit? There doesn't seem to be and release clips.

Thanks for the assistance.

Dave

[TrailDust]

There are a lot of past threads discussing ABS diagnostics, such as this one. You'll want to use the forum's search feature to locate others if the thread I linked to doesn't have the information you need.

[ds307]

Thanks for the reply.

I did perform the search before I posted.

I am looking for some specific information concerning the ABS code when there is no flash, indicating "Malfunction in ECU"

I was unable to determine how to remove the ABS ECU connector.

I also wanted to know if there are any other conditions that would cause the malfunction code.

Dave

[ds307]

I was able to remove the ABS/ECU connector.

One more question:

Can the ECU be replaced separately from the ABS hydraulic unit?
I probably need to replace the ECU but would rather not get into the brake hydraulic if I can help it.

Dave

[fenixus]

Is this the Bosch ABS (no traction control) unit with ECU integrated on a side of hydraulic pump?

PM me your email, I can send you the FSM diagnostics instructions for it.

there is 3 basic things you can check to see if ABS ECU works correctly, in short:
a) first jumper pins Tc and E1 in DLC1 under hood and see if you can read codes
b) then try entering the speed sensor diagnostic mode by jumpering Ts and E1 in DLC1 under hood and follow a driving pattern to see if you get special speed sensor diagnostic codes (different from regular codes)
c) check voltage/resistance/continuity between some pins in DLC1 terminals and pins/terminals in ABS ECU plug (which mounts on the ECU on pump)

If you pass all of above then the ECU is likely good and problem is with sensors (or their wiring) or speed rotors mounted in hubs (rear) or on axles (front) like missing teeth or so.

sometimes this ABS system seems to be working correctly with 1 or more persistent codes (but not engaging right) and you can do a) (because it lights up with codes), but can't do b) and fail c) - this equals a bad ABS ECU still.

Generally if you can't enter the speed sensor test mode it means the Bosch ECU is fried. as a confirmation you check some continuity or resistance or voltage (can't remember) between DLC1 and ABS ECU plug and if no voltage/resistance/continuity present then the ABS ECU is 100% dead (sorry can't remember such details on what check that was).

I can try finding a thread where I was doing this troubleshooting somewhat described on a V6 with Bosch ABS (no traction control), ended up replacing the whole ABS pump with working ECU from ebay at $100 shipped w/ lifetime warranty from wreckers as I could not find anywhere just the ECU for it.

EDIT:
ABS error 36 - open circuit - left front speed sensor or circuit