2000 gmc sierra bypass problem

I just installed a Viper 5704 on a 2000 GMC Sierra truck. I used a GMBP bypass module. Everything works fine until I try to remote start it. It cranks, but it will not start.

Now here is what I tried so far:
Tried remote starting with the key in ign turned to run position. It starts and it will also stay running on the remote start if you remove the key.

Tried reprogramming the bypass module dozens of times. The light blinks 4 times indicating that it is programmed, yet the truck will still not remote start.

I then tried grounding the brown trigger wire on the bypass module directly to ground when remote starting. Still no start.

Cut the purple data wire because the wiring info says to hook that wire up last and after the harness is plugged in. So tried wiring that up last, then program it again. Still no dice.

I ended up buying a 2nd bypass module. Then tried all the same steps as above, still no start.
What am I missing here??

Sounds like your missing ignition. If it starts with key turned in cylinder . And you ruled out bypass.
Check to see if your getting ignition to large pink and large white on the truck side

I agree with metz. You can also try just inserting the key (not turning it) and see if it remote starts. That will rule out ignition vs bypass issue. Not connecting the large white 2nd ignition can cause automatic transmission damage on that truck so check the connections carefully.

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Kenny
Owner / Technician
KKD Garage LLC
Albany, NY 12205

The ign is good. I checked both the pink and the white. You mentioned "large white". On this truck its a 16 gauge white. The yellow starter wire is also 16 gauge.

The owner of the truck said that it has a custom engine tune by Nelson Performance. Could the tune be possibly "blocking" and databus bypass signal? I know for sure that a tune can eliminate passlock altogether, but can it lock it?
When I say I know it can be eliminated, I know people put truck engines and computers into other vehicles like a hot rod that does not have passlock 2, and the engine tuning software can just eliminate the passlock so the engine will start and run.

Anything is possible with a tune, but I would think that it would be eliminated all together. Try starting it with the key just in the ignition (not turned to on) and see what happens.

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Kenny
Owner / Technician
KKD Garage LLC
Albany, NY 12205

Can't remember for sure, but I think I did try remote starting it with the key in, and didn't start. I turned it to run then remote started it, and it started. I turned the key off and removed it and it continued to run. I also started it with the key and then initiated the remote start and removed the key and it stayed running.
So you are saying that if it doesn't start with the key simply inserted in the ign then its a wiring issue? I was under the impression that the rcode from the ign tumblers isn't introduced to the Passlock system until the key is actually turned?
I know simply inserting the key will work when diagnosing transponder based systems, but with Passlock I am pretty sure I have almost always had to turn the key.

The fact that you can do pit stop pretty much eliminates the ignition wiring. So it sounds like a bypass issue. Double check (or triple check) all of your bypass connections and fuses.


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Kenny
Owner / Technician
KKD Garage LLC
Albany, NY 12205

I did more than triple check all my connections. I must have checked everything over and over again a dozen times. I thought the bypass was bad, so I bought a 2nd one. Same thing happened. I'm completely confused as to wth is going on here. The only explanation I can think of is the Nelson Performance tune.
I think my next step is to try bypassing it with resistors and a relay. But I forgot how. Its been 15 years since I did a bypass with resistors. I used to do that on VATS cars back before the days of bypass modules. Anyone have a link to instructions on how to bypass Passlock 2 with resistors and a relay???

I just wanted to update this. I got everything working fine by installing a PLJX self-learning Passlock bypass module. This module connects to the Passlock wires at the steering column BEFORE the signal goes to the computer. The other two bypass modules I tried using are the Databus type that connect to the data wire for the engine computer. But since the Nelson Performance tune locked the engine computer, there was no communication between the bypass module and the computer. So in a nutshell, if a customer has a Nelson tune on his/her GM vehicle, you will likely have trouble getting a databus bypass to work, so use the self learning type that connects to the Passlock wires in the steering column.