u1041

[01shavedblaze]

Hi all. I was driving the other day and was slowing down for a stoplight when I hit a bump and my ABS and BRAKE lights came on. They were both flashing for a while and now just the ABS one is on. My hypertech told me it's a U1041 DTC. I think the U1041 is "no communication with EBCM" but that doesn't help me very much. I checked the connectors on the EBCM and where the ABS sensors plug in on the frame, they are all connected. Does anyone have any idea what my problem is? I am not having any problems with the Speedometer or transmission shifting. Mine is an 01 extreme, if that helps any.

[BlazerLT]

Clean and reinstall the front speed sensors in the front bearing hubs.

[01shavedblaze]

Thanks for the quick reply.
I took them both out and cleaned them, cleared the code and it came back right away. Do you have any other ideas?

[BlazerLT]

No clue.

Might want to do a search on google for it and some clues.

[ricksza]

Code U1041 means that the other computers have lost communications with the EBCM. Usually it's a loss of power, ground or a bad module. There is a Service Bulletin pertaining to this concern:

PI00714A Follow the service manual diagnostic procedures and specifically check G110 at the radiator core support berfore replacing the EBCM. This ground is located on the driver side under the head lamp connections. This is the radiator support. I have also found that the radiator support itself has had high resistance to the battery ground.

[01shavedblaze]

Thanks for the tips again. My ABS started working again before I had a chance to check the ground. I had to make a quick stop and I could hear them work, but the light was still on. The light was out this morning so I cleared the code and it hasn't returned after a little test drive. I checked the ground anyway and found the screw is stripped and won't tighten all the way, I will have to fix that. Maybe she just needed a day after cleaning the sensors before the DTC cleared and light went out or the ground is not good all the time. Anyway, I appreciate the advice!!

[Rick Norwood]

Originally Posted by ricksza

Code U1041 means that the other computers have lost communications with the EBCM. Usually it's a loss of power, ground or a bad module. There is a Service Bulletin pertaining to this concern:

PI00714A Follow the service manual diagnostic procedures and specifically check G110 at the radiator core support berfore replacing the EBCM. This ground is located on the driver side under the head lamp connections. This is the radiator support. I have also found that the radiator support itself has had high resistance to the battery ground.

I found this thread doing a search. I believe I am having the same problem with my 2001 S-10 Blazer LT 4WD 4.3L. If my suspicions are correct, My ABS C0265 error code is a result of a bad G110 ground.

The gentleman that started this thread never gave Make model or year. Since his title is 01shavedblaze, I am wondering if his problem was on a 2001 like mine?

My Question is, is the G110 Ground on the 2001 S-10 Blazer LT 4WD located under the driver's side head light on the Rad support as described?

I have found articles on the internet that suggest it is under the driver's door on the frame rail, but there is nothing there.

[ricksza]

Originally Posted by Rick Norwood

I found this thread doing a search. I believe I am having the same problem with my 2001 S-10 Blazer LT 4WD 4.3L. If my suspicions are correct, My ABS C0265 error code is a result of a bad G110 ground.

The gentleman that started this thread never gave Make model or year. Since his title is 01shavedblaze, I am wondering if his problem was on a 2001 like mine?

My Question is, is the G110 Ground on the 2001 S-10 Blazer LT 4WD located under the driver's side head light on the Rad support as described?

I have found articles on the internet that suggest it is under the driver's door on the frame rail, but there is nothing there.

On full size trucks, G110 is near the body mount under the driver's door. The blazer G110 is on the radiator support.

[Southern Comfort]

DIAGNOSIS & TESTING
NOTE: When testing and diagnosing 4WAL system, use of Tech 2 scan
tool is required.
The Electronic Brake Control Module (EBCM) performs a selfdiagnosis
of the ABS system. The EBCM detects and isolated system
failures, then sets the corresponding diagnostic trouble code (DTC).
Before diagnosing 4WAL system, perform a comprehensive visual
inspection of system by checking wiring harness connectors, harness
routing (pay particular attention to wheel speed sensor wiring harness
routing), applicable fuses in fuse block, and ground connections.
Ensure brake fluid level in master cylinder reservoir is full.
Start 4WAL system diagnosis using DIAGNOSTIC SYSTEM CHECK. If
failures are found when performing diagnostic system check, you will
be directed to enter diagnostics to retrieve DTCs or perform SYMPTOM
TESTS. Diagnostic system check may indicate that system is functioning
properly.
C0221 .................. Right Front Wheel Speed Sensor Circuit Open
C0222 ................ Right Front Wheel Speed Sensor Signal Missing
C0223 ................ Right Front Wheel Speed Sensor Signal Erratic
C0225 ................... Left Front Wheel Speed Sensor Circuit Open
C0226 ................. Left Front Wheel Speed Sensor Signal Missing
C0227 ................. Left Front Wheel Speed Sensor Signal Erratic
C0229 ................................ Simultaneous Dropout Of Front
C0235 .................................... Wheel Speed Sensor Signal
C0236 ........................ Rear Speed Sensor Signal Circuit Open
C0237 ............................. Rear Speed Sensor Signal Missing
C0238 ............................. Rear Speed Sensor Signal Erratic
C0241-C0254 ................................... Wheel Speed Mismatch
C0265 or C0266 .......................... EBCM Control Valve Circuit
C0267 or C0268 ..................... Pump Motor Circuit Open/Shorted
C0269 or C0274 ....................... Excessive Dump/Isolation Time
C0271-C0273 .................................... EBCM Internal Fault
C0281 ......................................... Brake Switch Circuit
C0286 ....................... ABS Indicator Light Circuit Shorted To
Battery Voltage
C0288 ....................... Brake Warning Light Circuit Shorted To
Battery Voltage EBCM Relay Circuit
(1) - Always perform DIAGNOSTIC SYSTEM CHECK before performing DTC
tests.
DIAGNOSTIC SYSTEM CHECK
NOTE: For circuit reference, see WIRING DIAGRAMS.
System Description
The diagnostic system check is an organized approach to
identifying a problem created by an ABS malfunction. It must be the
starting point of any ABS complaint diagnosis because it directs to
the next logical step in diagnosing the complaint.
Serial data is exchanged by EBCM through harness connector
C1, terminal "F", and Class 2 data is exchanged through harness
connector C1, terminal "G". EBCM is supplied switched ignition voltage
through harness connector C1, terminal "A", and ground is provided
through harness connector C1, terminal "J".
Diagnosis
1) Verify all EBCM connectors are connected properly. Install
scan tool. Turn ignition switch to RUN position. Using scan tool, try
to communicate with the EBCM. If data is being received from EBCM, go
to next step. If data is not received from EBCM, go to step 4).
2) Using the scan tool, record any current or history DTCs.
If any DTCs are present, see 4WAL DIAGNOSTIC TROUBLE CODE (DTC) table.
If DTC(s) are not present, go to next step.
3) Turn ignition off for 10 seconds. Turn ignition switch to
RUN position and observe the ABS indicator lamp. If the lamp is on for
3 seconds then goes out, the system is operating normally. If not, go
to step 11).
4) Turn ignition off. Disconnect the 10-way EBCM harness
connector. Turn ignition switch to RUN position. Measure voltagebetween EBCM harness connector terminal A and ground. If the voltage
is between 10-15 volts, go to next step. If not, go to step 9).
5) Disconnect negative battery terminal. Disconnect 10-pin
EBCM harness connector. Check resistance between negative battery
terminal and 10-pin EBCM harness connector terminal "J". If resistance
is 0-2 ohms, go to step 6). If resistance is not 0-2 ohms, go to step
12).
6) Inspect EBCM and EBCM harness connector terminals for poor
contact. Inspect battery terminals and battery cable terminals for
poor connection. Repair as necessary. Is there a poor connection, then
go to step 7). If connections or terminals are okay, go to step 8).
7) Repair the poor connection. After repairs, go to step 1).
8) Reconnect EBCM harness connectors and battery terminals.
If communications cannot be established between scan tool and EBCM,
try scan tool on similar vehicle with the same system to determine if
scan too is malfunctioning or if Class 2 data line is faulty. See
appropriate diagram in DATA LINK CONNECTORS article in WIRING
DIAGRAMS. Repair or replace as necessary.
9) Disconnect positive battery cable. Turn ignition switch to
RUN position. Measure resistance between the positive battery cable
and terminal A of the EBCM. If the resistance is 0-2 ohms, go to next
step. If not, go to step 13).
10) Turn ignition off. Remove 10 amp ABS/Brake fuse. Measure
resistance between EBCM terminal "A" and ground. If the resistance is
infinite, go to step 15). If not, go to step 14).
11) Observe the ABS light. If ABS light stays on, go to step
18). If not, go to step 21).
12) Repair open or high resistance in circuit No. 451. After
repairs, repeat step 1).
13) Repair open or high resistance in circuit No. 441. Check
10 amp ABS/Brake fuse. After repairs, repeat step 1).
14) Repair short to ground in circuit No. 441. Check circuit
breaker. After repairs, repeat step 1).
15) Inspect ignition and brake switch input circuits and 10-
pin EBCM harness connector C1 for physical damage, which could cause a
short to ground with EBCM harness connector connected to EBCM. Repair
as necessary. If damage is found, go to step 16). If no damage is
found, go to step 17).
16) Repair damaged terminals. After repairs, go to step 1).
17) Check 10-amp ABS/Brake fuse. If the fuse is good, replace
the EBCM. After repairs, repeat step 1).
18) Use scan tool to turn off the ABS light. If the light
goes off, go to next step. If not, go to step 20).
19) Replace the instrument cluster. After repairs, repeat
step 1).
20) Replace EBCM. After repairs, repeat step 1).
I hope this helps. I do have the schematics for the abs as well.
Thanks
SC