I'm starting to feel like I’ve made a mistake getting this car. (Modded 2000 C5 A4) Literally every move I make to improve something the worse it gets!

If anybody has seen my recent post, I’ve been fighting for my life to fix the damn reverse lights. After exhausting most all of the recommended things to check I decided to slide under the car and evaluate the park reverse neutral switch. Lo and behold, it appeared that both connectors were only partially plugged in courtesy of the GM electrical connector glue substance. So I took a heat gun to the connector and plug to get the "glue" soft enough to plug them in all the way. Everything looked pretty good so I plugged them back in and managed to get them plugged in all the way.

Hopped up in the driver seat to start it feeling pretty good and going to check the backup lights. I get a split second of starter power as I let go of the key (not as I first turn it to “start” but when I let go*video in post 2*). I also managed to have a security light on the dash now.

I literally reached in and started it yesterday no problem.. today no go. The only thing I’ve done was make sure that the shifter selector switch was plugged appropriately. Can’t get by with that on this car. So I don’t know if this is truly a VAT thing or simply the shift selector switch under the car, causing all the issues I don't know. I’m ready to just get rid of the thing almost but I'm stubborn enough to keep it.

What’s the best way to start completely bypassing and getting rid of all this stupid crap that eliminates you from being able to even use the car!

I haven’t even started asking about why the headlights seem to be dimly lit after they’re closed and turned off, or chasing blinkers and running lights that don’t seem to work.

 

Ignition behavior below.

 

The switch has to be adjusted so it's synchronized to the transmission, the shop book shows the special tool to do this. Once that is done the shifter needs to be synchronized to the transmission using the rear cable end connector.

 

So do you think somehow when I plugged it in I misaligned it somehow if it wasnt tight enough? I ordered a new switch as there was a crack on the housing which probably has compromised something in there as well.

 

Stick guy here. Have owned a GM auto in the last millenium.

This sounds painful and strange. I'm mostly in to see the solution.

I have had reverse light and dash/interior lighting issues in the past but it was fuse related and therefore ground related.

I don't know your history with the car or the problem but with the C5s often there first, second and third solutions are to refresh the grounds. When you do, add some no-ox-id or similar to preserve them if exposed.

 

If you are having strange electrical gremlins I'd also lean towards a ground issue. Clean them all and reattach them and don’t put anything in between the rings and the frame. No dielectric grease, I wipe down the connection points with denatured alcohol.

 

So this was an opportunity for you inspect the connectors at the PNP switch, and use your test light to verify 12v in and out.....but it does not sound like you did that. It also does not sound like you inspected the connector contacts, switch contacts, etc.

and............ the PNP switch controls the theft deterrent relay....which controls the starter. That does not explain the security light, but more troubleshooting will reveal. First step is pulling DTCs.


If your first inclination is to start bypassing and deleting the saftey mechanisms ....then you are over your head, and will only add more undefined variables to the equation. No offense intended, but this is what happens when you are not familiar with a platform, common problems, and what to look for before purchase. So here you are. Two paths......sell it, cut your losses before it becomes a money pit.....or stay the course and systematically resolve the issues. Provided this is not a salvage/major accident or flood car.....it can all be resolved.
Your immediate investiment should be in a factory service manual for your car so you can gain a full understanding of how everything works and have full access to troubleshooting methods, schematics, etc. Your ability to make decisions and work on your car should not be dependent on a connection to the internet, forum, etc.

The first step in troubleshooting any vehicle since 1996 is pulling DTC codes and posting them for feedback. A service manual will also tell you exactly what do next based on the DTC.

My advice would be to get it running again, and sell the car.

 

Not so much in over my head (other than not having manuals in hand) just a bit frustrated. I’ve probably built 8-10 cars over the years that were deep builds including full drivetrain swaps, trans conversions replacing harnesses etc, engine builds, Turbo setup fabrications, tuning and so on. I can work my way around a car just fine and troubleshoot.

I did check the connections and the contacts all seemed corrosion free. As stated there’s a large opencrack on the switch itself which seems pertinent to replace anyway. I had to leave for work and couldn’t spend extra time in the moment. I saw zero need with a 15 minute window to drag a meter down there after seeing them partially unplugged. The “start simple” concept would prompt making sure they are plugged in all the way I would think.

Are you telling me you are the rare proponent of making sure you don’t bypass Vats? You’re on a short list with that one lol

Anyway, for purposes of relaying info I’ll be sure to let you know what I find out. No reverse lights combined with a cracked partially plugged in PN safety switch that caused a no start when it was the ONLY component touched in any way screams to focus on that part. So I shall.

It seems going through and servicing all the ground connectors is probably a good baseline on this car as clearly there’s a few gremlins to chase.

Definitely good advice on getting the manual in hand. Appreciate the input as always!

 

And from the thread I caught in the performance page it sounds like the prior two owners were not hot rodders. I've bought cars before from seemingly competent owners only to discover some horrendously poor work. The worst part is not knowing what they've touched or not and having to chase the whole car. That's where my comment about finding a bolt-on only car and adding a blower came from. It's hard for someone to mess up a header or intake install. And if they do, it's easy to locate their mistakes.

 

I agree 100% it’s always a risk.. and I definitely took it so only myself to blame. Which is probably what will motivate me to stick with it and resolve the issues. As lucky said it’s all resolvable. Just have to work through it. Luckily I only gave what the modifications on the car cost so I could borderline make money just parting the thing out lol. But that’s not my style. She’s not deserving of that fate 🤣

 

I'm sure I am. You are better off going with whatever everyone else is doing.

 

Well, then anything else is fixable for sure when it comes to electrical. It is just a matter of chasing it all down.

There is that teeter point at which it becomes easier to just redo sections of harness to ensure they're good. Though your problems sound to be largely localized to the chassis harness along the tunnel.

 

No-Start Resolved: PRN Safety Switch Replaced.