08 Yukon Aux Trans Pump Module Issues

[Ianh23]

Long time lurker, first time poster. I've got an 08 Yukon that I've been slowly repairing, luckily through warranty claims on the most Hybrid issues. Long story short, I've had the P0C2B and P0AC4. In January a shop started the process of going through the repair process.

We started with the control module. We think we got a bad one since Auto Stop's been disabled since the replacement. But the pump was also bad so we tried replacing the pump and did that with a brand new part in March... still had the codes and Auto Stop was still disabled. Around that time the hybrid pack was replaced too.

Here's the issue. We have the adapter for the module to pump connectors, but we can't find one for the module to (what I assume) the truck connector. The new module we got is out of a 2010 and the connectors are slightly different. So, the options are to either splice connectors or try ordering an older module.

Here's my hold up on the two options. If we go with an older module, I'm worried about the lifespan I'll get out of it so I'm kinda leaning against that. But with splicing, if it doesn't fix the codes then we can't send it back and I'm out the cost of the module. Looking for any advice on how I should proceed or if we overlooked anything. Appreciate any responses and anything helps!

 

[j91z28d1]

have you seen the tsb on the aux pump? I believe it's 24259588. unless you have that one already and need the other side. I thought those were the same module to pump.


P0C2B Transmission P0C2B
Auxiliary Oil Pump
(TAOP) Feedback
Signal out of Bound


that's a interesting one. I have a feeling that would keep it out of auto stop, since going into auto stop without a working aux pump would be very bad for the tranny.


the other one(P0AC4) is just the hybrid module requesting the ecm to turn on the check engine light. I don't know that that module needed changing first without a code saying the module itself has a fault. the aux pump would be first fix. as that's probably why it was requesting the light on. but as long as they programed it to the truck, no biggie.

if I'm remembering right, keep gust 2010 and up aux module. something about it was better if I'm remembering right.

 

[j91z28d1]

actually, you probably do need this side huh.

24259590

Service bulletin for hybrid bump/jerk issue

Hi. I have been experiencing what has been called the "bump/jerk" on GMC hybrid trucks. The symptoms include a jerking sensation as the vehicle switches between hybrid mode and engine mode. This can also cause pauses in acceleration or also sudden accelerations at low speeds. This is...

www.tahoeyukonforum.com

 

[Ianh23]

Looks like we've been following what that post says. I read it back when this all started, but it's been a minute. We did the module first, then the pump since the issues were still there, and so now we're back at the module. Whether it was just the module or not, replacing the pump was needed anyways since it was making noises and seeming to fail.

One thing that I remembered this morning. When he replaced the module the first time in January, he did testing over two days with no lights on the dash and nothing in pending. By the time I picked it up or the next day, the codes came back. So could the old pump caused the new module to fail? Or I guess it could be possible there's a wiring issue.

We have the 24259588. That leaves the other side. It's got 5 wires. I added some pics of which one it is. When I looked up 24259590, all I got was this. It doesn't seem like that's what I need, but I could be wrong. I think I've headed the same thing about the 2010 and up modules, but couldn't say from where. So I definitely want to use the new module if it's not a truck side problem. Not sure what the best course of action forward is.





Let me know what I'm missing or any suggestions. I'm open to hearing anything!

 

[j91z28d1]

I'm honestly not sure.. how I read it the long mess of wires 24259590 is what you need, but without seeing it in person. I can't really tell.

there is this one, 24259588

but it looks like to what you already have? let me take a look under my hood tomorrow and I'll see if I can tell what mine looks like. mine being an 11, it wouldn't have the adapter harness, but maybe get an idea of the plugs. but you definitely have the aux module to aux motor connected up right?

 

[j91z28d1]

so I reread your post. I don't know where my head was when I read it the first time. ugh, I read it as you replaced the aux pump and the the hybrid module, like the one inside the battery pack. then a hybrid battery itself and then trying to update the aux pump module because of the code. ugh.

so yeah, pump making noise, replaced. now P0C2B code module. not a bad thing to update it to the 2010 and newer at that point. Just need the correct part number for the retro fit harnesses that make it plug and play.

honestly, I might stop by a gm dealer with that tsb that shows the modules upgrade info and have them pull up an exploded view of those 3 part numbers and see which one you need for your application. I do have a feeling it's 24259588, but it's a 50$ guess.

here's some other info I pulled up on that code. incase you need it, or still have issue after you get it running. the aux pump module does not need programming, as you probably knew. Just double checked, also this code will keep it out of auto stop. the aux pump module itself has no codes stored in it. the other modules set codes based on got getting the correct info from it.

anyways, I think you will have fixed it once you get that wired in.


oh, I added the module wiring diagram for a 2011 as well. incase the newer truck had different wiring colors or anything. they seem 99% the same. Just the diagram itself laid out a bit different.

 

[Ianh23]

Yeah, we've got the 24259588 on the pump side of the module. The other side is the one that maybe the 24259590 would be for... Still not 100% sure but I might stop on down to gm dealer later. It's honestly such a minor looking change between the connector on my truck and the newer module, just the pins/connectors are slightly differently arranged.

I appreciate the help, this has been really helpful. I did some research about a year ago when this all started but once I got the shop involved in September I haven't done as much digging. So this definitely refreshed my mind on all the little quirks.

Ultimately the quick and dirty way to resolve it would be to splice the connector from the current module onto the new one. They're both 5 wire it seems like things would connect the same.

If any additional information pops up or any other suggestions, I'm all ears.

 

[j91z28d1]

so here might be the confusion. there's 2 part numbers only 1 number apart and they both look almost the same, but I think one is tranny side one is harness side.

24259588 and 24259589

if you open both pics side by side they arw different adaptors.

Disregard 24259590, I think that's something else.