I Need Help Finding VSS and Injector Signals

[Axaday]

My dad and I thought it would be easier than it is and after a few hours of trying, we found that we need more information. Our methodology was to poke insulated wires with a sewing pin and test the needle.


I found the VSS and it had a purple wire and a yellow wire coming out of it. We traced those wires up to an accessible location, but we can't figure out what the signal is and which wire is bearing it. One of these wires just needs to be tapped, right?

The other might be more embarrassing. We're pretty well certain we found an injector wire, but again there were two wires, a green one and a black one. I assumed that the green one would be the signal and the black one ground. We tested the green one and it read around 12 volts DC when the engine was running. Just to check, I poked the black wire and when I did there was a spark and the engine died. I've started the engine a few times since and the car runs funny, like perhaps I killed one of my injectors? It isn't a huge concern to me if that's what it is, because the car is very old and valueless and I'm already planning to replace it, but I'd like to understand what happened and more importantly what I need to do in the future to find these two signals.

[ptsmith24]

What's the year/make/model of your vehicle? Someone may have the same one as you and could help you out. Also, you could go get a Chilton's or similar manual. I haven't checked my manual to see if it has the necessary information in it, but will probably get around to it this weekend when I'm ready to install.

[SVOboy]

I would search online for "[year] [make] [model] ecu pinouts" and then use that info to find the wires on your ecu and trace them to where ever you want to tap them.

[Axaday]

Originally Posted by ptsmith24

What's the year/make/model of your vehicle? Someone may have the same one as you and could help you out. Also, you could go get a Chilton's or similar manual. I haven't checked my manual to see if it has the necessary information in it, but will probably get around to it this weekend when I'm ready to install.

It is a 1989 Pontiac Grand Prix. I have a Chilton's manual, but it doesn't contain the necessary information. It is a thick book covering all cars from that year and not one specific to the car, if they make that.

Originally Posted by SVOboy

I would search online for "[year] [make] [model] ecu pinouts" and then use that info to find the wires on your ecu and trace them to where ever you want to tap them.

I was googling "1989 grand prix vss wire color" and a few variations on that, but I just tried what you suggest and I get nothing useful. There seem to be things for cars just a few years newer, but not for mine.


My question, I think, is a more general than this, though. I'm pretty sure I have it narrowed down pretty tight, but I want to know what I'm looking for. Is there one wire to tap for each signal? What kind of signal does the wire have, so I can confirm that I have the right one?

Oh, and...is there a wire that, if grounded, can destroy an injector?

[SVOboy]

Well, your vss is different from mine (mine had a signal, ground, and power wire) so mehbe it's self-grounding, but the signal wire should pulse 12v-0v as the wheels turn. So I'd try the non-yellow one first, tap it with a DMM, and roll the car a bit with the key in run.

[Axaday]

Originally Posted by SVOboy

Well, your vss is different from mine (mine had a signal, ground, and power wire) so mehbe it's self-grounding, but the signal wire should pulse 12v-0v as the wheels turn. So I'd try the non-yellow one first, tap it with a DMM, and roll the car a bit with the key in run.

Yes, that's what I need to know. Thanks! Hopefully I can work on this again tomorrow afternoon.

[Axaday]

Ok, my car isn't short one cylinder. It's short three. Because the fuse blew. So that part is solved. The car is okay.

Can someone tell me what the Injector signal is like and how I will know I have the correct wire on it?