Cliff notes - While wiring electric water pump, I think I tripped/fried the theft deterrant module on my car... that i didnt even know it had until now. Or possibly fried the PCM.


going to keep this short as i possibly can: Tonight I was over my buddies wiring the relay harness for my electric water pump. I couldnt really find any "popular" choice for a 12v signal for the ewp relay, so I thought I would be creative and use the same signal as the fuel pump, since that has a nice automatic function to it. (shuts off when engine doesnt start).

I looked up the wire in a haynes manual, A25, and spliced it in. *THIS ISNT CORRECT* (also can be found here: http://shbox.com/1/1995_pcm4.jpg). I turned the ignition a couple times and it sounded like everything was working as it should be! So i cranked it over and it fired up... but it immediately died. This didnt alarm me since I just did a cam swap and the tune isnt right. Fired it again and exact same thing. but this time all the lights went out and the car went COMPLETELY dead as if there were no battery even connected.

So, fast forward a little and this is about when I double checked the schematic and noticed where that signal wire was going ... the theft deterrant module, instead of the fuel pump. Yea, brilliant of me.

In the time I had, I managed to track down the relay for this module and test that it is functioning correctly. I was hoping I just fried that relay but no dice. the PCM also SEEMS to be OK considering everything comes back when the battery disconnected/reconnected, but it goes out the instant ignition is turned.

Can anyone here either tell me what I did, or if not tell me where the theft module is? Or any other ideas? I want to get the car out of my friends garage. I have already removed the splice, if that wasnt obvious.

 

well I am completely confused now... as I am finding instances of this being done successfully before.

http://www.camaroz28.com/forums/showthread.php?t=445168

 

Might sound dumb but, if you think you fried the theft module, why not just delete VATS and see if that solves your problem?

 

no its not dumb at all, I just didnt have time to get that far tonight. Its also not something I really want to bypass, but I will definitely try it tomorrow if i have to. I dont know what it entails but I will figure it out tomorrow, I am completely exhausted right now.

 

VATS is supposed to throw a security light on the dash... mine isnt doing that. My PCM must be toast

 

Yea it tradionally would, I say disable it for now, if its not the case, borrow a pcm from someone and see if that works. Sure you didn't just pop a pcm fuse or some other fuse?

 

Check all ur fuses in the driver's door fuse panel.

 

If I knew he may have fried his PCM for some wiring, I would never let him borrow my PCM.

 

This is what I would do. Check all your fuses to make sure nothing popped and then use you ignition fuse for your w/p relay like everyone else. Just friction fit it under the blade fuse in the engine compartment.

 

Joeilus, you really should have used pin A7 " http://shbox.com/1/1995_pcm3.jpg " that is the +12 pick to the fuel pump relay. Pin A25 is a 50hz square wave FROM the Theft Deterrent Module that tells the PCM that the correct key pellet was used and it signals the PCM to allow the fuel injectors to pick. If TDM is working correctly the security lite should come on for 5 seconds when key is turned on then go off. TDM then picks the TD relay which allows the starter solenoid to pick and also sends 50hz (pin a25) to PCM to allow fuel injector pick. Take off the wire to the EWP relay and see if the car starts, that means TDR is OK. If security lite stays on then TDM is not working. Tyeing pin a25 to the EWP relay pick should only have grounded the signal (thru the pick coil) it does not seem grounding the TDR signal to the PCM should blow anything, but it could be a first.

 

Agree with everything you said. Thanks for the pointers. I also do not understand how i blew it up. (if i did)

BUT i picked up an extra PCM out of an LT1 caddy today for $50 so we shall see if thats the story. I figure for that price i might as well have a spare anyway. I already removed the EWP relay, so everything should be as it was. Im gonna give the new PCM a shot after work.

nor would i risk somebody's else's

 

Looking at this diagram:
http://shbox.com/1/pass_key.jpg

Im guessing somehow we grounded out pin A25 right next to the pcm. By looking at that diagram, it appears that would draw too much current through the pcm. Is this assumption correct?

 

Sorry To Hi Jack But I Just Bought A Motor That Came With An Ewp, Where Can I Find A Good Schematic To Wire It Up??

With Or Without The Safety Light I Hear So Much About I Dont Need It To Be Fancy..just Work...ill Even Use A Toggle If Needed Lol


Thanks And Sorry Again

 

Turns out the terminal for the 12v+ was loose causing all the wires to be loose on it. Pcm is just fine. I dont know where you get a schematic, sorry. Id imagine if you search a tiny bit you could find one easily.

 

Just following up to what jon said, I am now tapped into pin A7 and its working just fine.

I am a little amazed at my luck with this stuff, and I dont understand how a slightly loose accessory post killed the ENTIRE car, but it did.

On the bright side I have a spare PCM now which is a good thing because I am going to be reflashing it alot.

 

ya, i had searched before i even wrote.......

but thanks phenomic, you were a big help.