I am about to verify the pump, and have found a used pump assembly since reman are no longer available. Where did you get the motor from?

 

I got my motor from another used pump.

 

New module, used pump and valve body. I bought an Autel 808 and it only talks to the truck intermittently. I went to the splice pack under the dash and there are only 2 wires 1 in and 1 out.

when I was able to talk using the Autel it showed the ABS relay as on and it would not command off. When I hit the brakes it sounds like the pump is running. Is the relay supposed to be on all the time or only when commanded?

 

The relay should only be active when commanded by the ABS module.

Try swapping the relay with one you know works (horn or ac compressor relay).

I’ll have to find more specific info about the code/circuit before I can advise you further.

 

I think the relay is part of the ABS control module, but I will go look at the relay box labeling and test. It appears to me constant power is delivered then the module activates the pump internally. Most recently I have been looking for a problem on the class 2 serial network, mostly because my new Autel-808 does not reliably talk with the truck. Looking at All DATA Data Link Communications diagnostics it is looking for a U-1000 through U-1254 not the C0110 code I have been getting, so I may be barking up the wrong tree.

I am starting to think the module I bought is defective or the wrong part for the truck. Aside from various tests I have:

• Replaced the control module with a new one and had the dealer to program it. No change to the problem code C0110.
• Replaced the pump valve assembly with a used one (they are no longer available or repairable) No change still code C0110. I used the newly installed control module with the used pump
• Bleed the brakes, manually because I can not use the auto function Even when the Autel 808 will talk the code C0110 blocks it.

I have ordered another pump/valve assembly and will switch the used control module with the one that came with the junk yard one while I wait on the new/used pump. Unfortunately, I don't have the original module.

 

You may want to check the ABS module motor, as they have been found to ruin ABS modules by dwawing too many amps creating a,greater then normal, load on the relays. Over time, the created heat load, weekens soldered joints, then they fail.

 

Sorry for the delay in getting this posted - I’ve been busy.

Is your truck GVWR above or below 8600 lbs? There’s minor differences in the ABS system if so, and it’s possible the replacement module you got is for the wrong GVWR.

Have you verified the circuits for the pump motor are in tact at the ABS module? IIRC, the pump motor has a separate, 2 pin connector. Get an older halogen headlight (square style) and use jumper wires to put the headlight in place of the pump motor. The power & ground circuits in the harness are almost a direct connection to the battery, so if the headlight glows brightly, the circuits are good.

First check the headlights brightness directly at the battery so you have a brightness level for comparison.​​​

 

The truck is a 2004 Silverado 2500, 2WD, gas powered. I am pretty sure it is below 8600 GVWR (my so has the truck so waiting for him to verify, or I will double check when I get it back) it has the HVY RPO code, so that may make some resellers think it is over the 8600#.

I put 12 volts on the original pump after it was removed; it hummed and drew about 1.5 amps. I guess the test you are recommending is done with:

• The module plugged into the truck but disconnected from the pump to give access to the terminals.
• Use the scan tool to command the relay on if its not already on.

 

The scan tool and/or module isn’t necessary for the test I’m recommending.

What you’re testing is the integrity of the circuits that provide power & ground to the pump motor. Keep in mind that 1.5 amps is what the motor is pulling without a load - but its intended purpose is to create hydraulic pressure, so it likely needs 5-10 amps to work under load.

If the circuits that provide power & ground aren’t able to deliver enough current, the pump won’t run (or won’t run as expected) and all the ABS module “sees” is the pump isn’t doing what it’s being commanded to do. The module doesn’t have the capability to analyze why the pump isn’t operating as expected, so it defaults to the C0110.

See the attached diagram for a better idea - the circled connector will be disconnected and the headlight connected between the power & ground circuits on the harness side.

 

OK, Thanks for the clarification. In summary I am verifying the truck can can deliver the power needed to drive the ABS pump.

I put a multimeter on it and got 12+ volts but very little current and no activity from the pump.

A new / used pump and valve assembly arrived yesterday and I will run the load test you described before installing it.