2002 LQ9 swap everything from same donor truck engine, 411 pcm APP (pedal) and TAC module. I owned and drove donor for two years prior to swap it had zero issues. As soon as I turn the key on my fuel pump relay starts clicking continuously if I pull relay and install test light it pulses the entire time with TAC module connected. If I disconnect TAC and power up pcm the prime signal comes on for 2 seconds then off as it should. When the TAC is plugged in the TAC motor on the throttle body has a slight hum and if I hold a finger on it I can feel the exact same pulsing that is showing on the test light. If I unplug the 2 wire connector Brown and Yellow I am getting HIGHER than battery voltage 13.0 with battery at 12.7-12.8.

Tuner has removed vats, egr, evap, ac and automatic transmission controls as this will be a t56 magnum.

I have been over every single wire from the pcm checking both continuity and resistance. Serial data lines from TAC to PCM are good and only about a foot long.
ALL GROUNDS are clean, tight and secure about 100ma voltage drop on grounds from battery voltage, Added additional ground straps from frame to block and block to firewall.
5V ref wires testing good.
APP checks out good.

PCM and TAC are powering up at the same time.

I have an extra pedal and tac module tried swapping both no change.
I THOUGHT my original pcm was bricked wasted money on a brand new pcm, having my operating system reinstalled and having to pay another 2 credits to have my new pcm unlocked. It does the EXACT same thing.

When the TAC is connected my code reader cannot connect to the pcm as soon as I unplug the TAC module it can talk to the pcm no problem.

I know 02 is kind of a odd year that the APP actually uses all 3 sensors in the APP but if I leave the pedal disconnected it still has the issue.

The big red flag to me is the HIGHER than battery voltage at the TAC motor on the throttle body.

I am open to suggestion I have been scouring the internet for weeks and the ONLY other person I found with similar issue stated he had switched to either a Fbody or corvette manual trans tune. The 6.0 was never offered in an escalade with a manual trans. I am not sure if you could get a manual trans with a 6.0 in ANY chassis so I am wondering if that has anything to do with it. I have been over each and every wire in and out of the TAC module to APP and back to PCM and I cannot find a reason for it to behave this way.

 

I'm not so great at reading comprehension, but did you say that everything is normal and the engine runs properly when the tac is disconnected?

Nick

 

I have not tried to start it with the TAC module disconnected. I will have zero throttle if I try that. I have an extra TAC module and tried swapping them out as well as another gas pedal and no changes. I am sure it is going to be an easy fix I just cannot understand how the TAC motor connector terminals are getting HIGHER than battery voltage when tested that really makes no sense to me.

 

Are you sure all your grounds are connected properly? Did you try a different battery? Just some simple things to check. Also is the pcm setup for the tac module or is it set for a cable driven throttle body since it is an 02.

 

Grounds are cleaned to bare metal good secure and tight. Brand new battery fully charged holds around 12.7-12.8v. PCM is set for DBW donor was an 02 escalade ext which came with dbw not dbc. TAC module, 411 PCM and Throttle pedal/wiring all from same donor truck.

 

What OS number are you using?

 

Post up the tune file. The part I don't understand is that you said with the TAC plugged in you can't talk to anything over OBDII but with it unplugged you can talk to stuff. That immediately makes me think the TAC module has somehow gone bad, but I haven't seen that before.

 

12212156

 

I have been away for a bit but still having issues. I do not have HP tuners so I cannot post the files the tuner I am using is who I have to work with.

**update**
Most recently he put in a Y-body manual trans tune and now I can get the car to start and run but I have ZERO throttle control. Which leads me to the next question is do I have to now use a y-body app and tac module. I know there are two wiring pin positions that would need to be swapped. I could be wrong but i **THOUGHT** the 02 trucks (though possibly also the 00/01's as well) were the ONLY ones that used 3 sensors in the APP where 03-05 only used 2 even though 3 are present.
I have a spare ecm that I am going to have him load the original stock tune from the truck and only turn off VATS and see if I get throttle control and just let it puke out the codes fro auto trans, ac, egr, evap etc and just see what it does.

My gut feeling is there is probably a segment swap and some other minor adjustments needing when setting it up for a manual trans and I get the vibe that may be out of his wheelhouse.

 

I have the same problem, did you ever get yours resolved? I’m stumped

 

Yes I will be posting a reply to another thread and you can see if it fixes your problem as well.

 

where can I find that thread?