GMT800 ABS Module repair

[clinebarger]

2004 GMC Yukon XL Denali with the dreaded C0265 "EBCM Relay Circuit Low"

Usually caused by a cracked solder joint at the Relay pins on the circuit board......But the Main Power & Ground solder joints can crack too!

*Yellow arrows are the relay pins.
*Red arrows are the Power & Ground feeds. They were good on this unit.
*The Blue arrow is a Isolator/Dump Valve Solenoid control I found cracked.

I reflowed & added a little solder to all 5 Relay pins & the Dump Valve pin. The cracked Dump Valve solder joint was a first for me.....But it goes to show WHY you need to go over the entire circuit board with a good light & magnifying glass.

Sometimes you need to apply slight pressure to the exposed pin to see the crack, A pocket sized flat blade works great! You can usually SEE the dullness of a cracked solder joint because a Cold Joint is what usually causes cracked joints!

I use a sharp razor blade in a box cutter to cut the RTV seal between the module & cover, Use Right Stuff or Ultra Black RTV to reseal the cover.
I put it in my vise with light pressure & let the RTV cure.

 

[ls1mike]

That is awesome.

 

[tiger862]

Great catch.

 

[Trav]

Nice!

 

[OVERKILL]

Great work

 

[supton]

Nice work!

 

[BMWTurboDzl]

What is that eraser colored material?

 

[supton]

Originally Posted by BMWTurboDzl
What is that eraser colored material?

Looks like thermal compound to me. To transfer heat from the PCB to the housing.

 

[nthach]

Good thing that Kelsey-Hayes/TRW ABS module was a standard PCB and not one of those silica-based substrates potted in clear silicone like the ATE/Bosch ones are.