2003 Trailblazer ABS light C0265

Zack2003

Original poster
Member
Jan 24, 2015
153
Hey guys new to the forum I just bought my wife a 2003 trailblazer with the 5.3. I had the ABS read and it was the Co265 code. I cleaned the ground under the driver Seat on the frame and it didn't do anything. What's my next steps? I appreciate any info given
 

IllogicTC

Member
Dec 30, 2013
3,452
DTC C0265 or C0266

Circuit Description
The ABS relay supplies battery voltage to 6 valve solenoids. The electronic brake control module (EBCM) microprocessor applies the grounds needed to activate each solenoid. The low side of each solenoid coil has a feedback circuit to the EBCM microprocessor. When a solenoid is commanded OFF, the feedback voltage is high. When a solenoid is commanded ON, the feedback voltage is low.

DTC Descriptors
This diagnostic procedure supports the following DTCs:
  • DTC C0265 EBCM Motor Relay Circuit
  • DTC C0266 EBCM Motor Relay Circuit
Conditions for Running the DTC
  • The ignition is ON.
  • The vehicle speed is greater than 6 km/h (4 mph) .
Conditions for Setting the DTC
The EBCM detects an internal malfunction.

Action Taken When the DTC Sets

C0265
If equipped, the following actions occur:
  • The EBCM disables the DRP/ABS.
  • The ABS indicator turns ON.
  • The brake warning indicator turns ON.
C0266
If equipped, the following actions occur:
  • The EBCM disables the ABS.
  • The ABS indicator turns ON.
Conditions for Clearing the DTC
The conditions for setting the DTC are no longer present and you use the scan tool Clear DTCs function.

Diagnostic Aids

Important: Whenever the EBCM is replaced for DTC C0265 or C0266, the ABS pump motor and motor circuitry must be tested for the proper resistance. Refer to steps 7 and 8 in the diagnostic table shown for testing procedures and resistance values.

C0265
Thoroughly inspect connections and circuitry that may cause an intermittent malfunction.

C0266
Replace the EBCM if DTC C0266 continues to set intermittently.

Since you've cleaned the ground, there may be a failure within the EBCM unit. It's not entirely surprising given its location gives it fairly high exposure to the elements, and road salt. The diagnostic procedure here states that examining the circuitry (by opening the EBCM case) may point you to an issue, and if you know your way around electronics it's worth a shot. If not, a new EBCM may be in your future.
 
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Zack2003

Original poster
Member
Jan 24, 2015
153
Man I appreciate the reply I'm ok with electronics I'll take it apart and see if I see any solder joints broken
 

Zack2003

Original poster
Member
Jan 24, 2015
153
Where is the best place to get a ABS module? I'm assuming from the dealer would cost a fortune
 

IllogicTC

Member
Dec 30, 2013
3,452
Zack2003 said:
Where is the best place to get a ABS module? I'm assuming from the dealer would cost a fortune
Do you have traction control? I've found 2WD units from Dorman.

W/O Traction control is Dorman part number 599-715 (GM Part 19148795)
WITH Traction control, it appears Dorman doesn't have a part. GM Part number looks to be 19244902.

They aren't exactly cheap but with the power of the Internet they can be had at a little cheaper price. Talk with the supplier on whether or not there is a core charge. If there is, you can send them your old unit to receive a rebate or partial refund. I see GMPartsGiant includes a $50 (!) core charge on their W/ TC unit, which is $400, which would mean knocking over 10% off the price.
 

Zack2003

Original poster
Member
Jan 24, 2015
153
Sad fully mine has the traction control. But even with the abs light on its working. I would have thought it wouldn't work.
 

Zack2003

Original poster
Member
Jan 24, 2015
153
So got my module out and took it part weird thing the top aluminum cover did not have any screws like the videos I have watched showed. I think I have found 2 pins with a cracked joint but I'm not 100% sure. They are so small it's hard to see
 

IllogicTC

Member
Dec 30, 2013
3,452
Zack2003 said:
So got my module out and took it part weird thing the top aluminum cover did not have any screws like the videos I have watched showed. I think I have found 2 pins with a cracked joint but I'm not 100% sure. They are so small it's hard to see
Could always try some multimeter measurements on the suspect pins in comparison to ones that look good.
 

Mark20

Member
Dec 6, 2011
1,630
Welcome aboard. Do stick around and help were you can.
 

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