I/P blank after swap. BCM getting power.

[AllBlackSierra]

00' 4.3 to 03' 5.3. All plugs (C2, C100, C152) are pinned to schematic. Key in on position, I/P blank except MIL light. Key in on position with scan tool inserted into DP, I/P lights up like normal with security light on which explains start/stall when turning motor over. Remove scan tool I/P goes blank again. Can't run PASSLOCK relearn without functioning PCM, BCM, and I/P. I compared I/Ps and BCMs between the years, and they are identical. Please any direction would be greatly appreciated guys.

[vortecyota]

I may not be any help here because I don't have any diagrams in front of me but the bit of info that stands out to me is the fact that the I/P wakes up with scan tool connected. There are two grounds at the DLC pins 4 and 5, iirc. The scan tool circuitry is likely connecting the two. Just a total shot in the dark but I'm guessing maybe the IP shares one of the grounds with the DLC and that ground is open somewhere.

Try grounding the two DLC grounds one at a time with a jumper and see if the IP wakes up. If so, trace it to the connectors you pinned or splice in behind the DLC and ground it. Post back what you find.

[AllBlackSierra]

So the good news, I sent PCM out for reflash and removed VATS. Plugged it back in vehicle started right up runs like a champ. I'll check the grounds in the AM and report bank ASAP. Thanks for help it means a lot.

[vortecyota]

No problem bud, please let us know what you find. I'm curious.

[AllBlackSierra]

Took the blk/wht ground pin#4 from the DP, grounded it, I/P lit right up! I'm still concerned why I have to ground off the DP.

[vortecyota]

Awesome! Makes since. Can't help you with where the open in that ground is but I'd imagine you could trace it to a mis pinned wire or missing pin all together. Last resort just tap in to that circuit and give it gnd.

Thanks for letting us know, not enough folks do that.

[AllBlackSierra]

I already spliced into that circuit and created a dedicated ground. I'll always report back. This is all about learning from other people's posted experiences, unfortunately most people find an answer and fix the problem they don't reply back cause they don't care. Now I just need to figure out why my oil pressure gauge is reading incorrectly or not at all. I'm thinking the 00' IP isn't registering the 03' data. I know 03'+ used serial data for oil pressure where as before it was a dedicated line.

[vortecyota]

My thoughts exactly! I learn a lot when I try to help... as long as the OP replies, lol. Thanks!

You may be on to something, if I get time this weekend I'll look thru an 03 cal and see if there are any oil psi output scale parameters. As of now, I have no idea.

[kewljay223]

so are you saying that your old gauge cluster didnt use serial data for the oil pressure??? and that it used direct variable voltage from the oil pressure sensor like the older trucks like mine (95')?? well if thats the case then i bet that explains your problem. if that really is the case, then sounds like your gauge wants the same voltage fluctuation which its not getting. if the 03+ motors go through the pcm, im betting the voltages from the newer sensor fluctuate between 0-5v where as the old sensor probably went from 0-12v which explains why your reading low. if your using the 5.3 sensor, im betting its supposed to go to the pcm which decifers it to serial data and then sends to gauge. but im guessing your going straight from sensor to gauge which is only supplying half of what the gauge needs. my guess would be to put your old oil sensor in and see what happens. if it works great. but then i would find it funny they used the same style connector but then again, why would GM spend more on changing connectors... IDK just a thought...

[AllBlackSierra]

I'll check out tomorrow. Ya 03+ had 3 circuits; a tan/wht pres sen sig, blk low ref, and grey +5v. 02 prior had a tan/wht circuit straight to I/P via C100 plug. What about inline 5v to 12v conversion?