2006 Trailblazer U1040

Joined
Feb 25, 2015
Messages
2,518
Location
Sask, Canada
2006 Chev Trailblazer 4.2, 272,000km.
First onset was spring 2020, abs and brake light intermittently came on while driving through slush and snow. Eventually it stayed on. Internet searches show that both lights on were related to ECBM issues and or ignition switch.

Ignition switch was swapped out with the lighter colored updated one. No change. Checked the ECBM ground on the frame, under the driver position. Cleaned it several times and even daisy chained it to two other grounds. No change. I just left it and drove it.

Now, I need to prep this vehicle for daily use again. Got a transfer at work and my oldest daughter is on the cusp of getting her license. Today I sourced an OTC Genysis or whatever it's called. P0412 and P0418 present but related to the AIR pump I tore off 8 years ago. Main code was U1040 ECBM connection issues.

Pulled the connector off the ECBM, the pins were clean and the wires leading into the pack appeared fine. Pulled the circuit board out, appears fine but unlike all the kelsy hayes units that litter the internet, I don't know the make or model of this one. So I am unsure if this model is prone to cracked solder joints.

Key on, engine off, the two main connector pins #2 and #31 have battery power. Both grounds #16 and #45 have next to nothing for resistance when tested to the ECBM frame ground.

So now I am at a loss for where to look next. Perhaps I dig through the wiring harness as the looms are full of dirt and grime, perhaps come across a busted wire. Anyways, thanks for reading.

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To add, when I said battery power to the positive pins, it was low. Battery was a bit low at 12.05v or so. The pins were showing 11.5v.
 
Trickle charger on the battery, reading 12.36v. Orange ignition wire, key on, 11.38v constantly over three 4 separate grounds.

Edit: checked pin 32 on the EBCM. It read 11.08v.

Checked other fuses in the rear block with ignition on. All are consistently in the low 11v range.
 
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You really need to load test the power and ground circuits for the EBCM.

Easiest way I've found to do so was to buy a 9006 headlight pigtail and use it in conjunction with a 9006 bulb. Makes for an easy way to test blower motor resistors/modules that require a load in order to function, as well. If the circuit can power a headlight bulb, I'd be suspecting the EBCM even if you can't see any bad solder joints.
 
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