C-5 wont start, no power to anything

[Pags]

Yea, it's a shame though that the bank is gonna sell the entire car for salvage for about 3k, when the engine and trans have about 25k invested in them.

 

[dadaroo]

You can arrange to buy the car from them and recover a lot of cost by putting those parts into another car or selling them by parting out the car.

 

[Pags]

So good news! The car isn't totaled. The tow company did about 5k worth of damage but it's getting fixed. So now I guess it's back to the no comm issue. Do you guys think I should get another 98 pcm? Or go with something else?

 

[dadaroo]

I will not try to tell you which way to go, but, finding a 98 PCM may take a while but they are out there. Try NAPA, Rock Auto, GM, and others.

Also, you can send yours into Cardone, NEC, etc. and see if they can fix.

Last resort you can upgrade to a newer PCM but you will need to rewire the pins which is not hard, just time consuming.

Here is the link on doing that to get an idea of what it takes. Just remember you need to verify the old pin outs versus the ones required for what ever newer year you are using. You will need to have both FSMs since there is no one schematic showing the PCM pin outs. They are spread out over the entire 3 volumes.

HOW TO 99-02 PCM into 97-98 Corvette - Corvette Forum

Let us know what we can do to help further.

 

[KANE]

One more thing, make sure that your battery cables are clean and tight. After cleaning and tightening the cable bolt, make sure that you cannot twist the cable ends back and forth by hand, sometimes the bolt can be tight and the cable is still loose on the battery terminal. Good luck with it.

^ Great advice!

On my old C5, the terminals actually separated from the battery. I had never seen that happen in 20+ years! But it can- and it will throw low voltage codes etc.

So yeah, check your connections first!

 

[Pags]

I wouldn't mind getting another 98 just to make it easier, but I'm afraid I'll run into the same issues down the road if I get another 98. If I can find all the schematics I'd be fine with swapping it out for a newer one. I think that would be best so I have some more versatility down the road.

 

[LLC5]

I wouldn't mind getting another 98 just to make it easier, but I'm afraid I'll run into the same issues down the road if I get another 98. If I can find all the schematics I'd be fine with swapping it out for a newer one. I think that would be best so I have some more versatility down the road.

Just for S&G's (and curiosity), has the electrical portion of the ignition switch been replaced recently?

 

[Pags]

No not replaced, but I did take it apart and cleaned all of the contact points inside

 

[LLC5]

No not replaced, but I did take it apart and cleaned all of the contact points inside

Here's the thing with cleaning electrical contacts, if you used anything more abrasive than an eraser to clean the contacts then you could have made them worse. If there was any pitting on the contacts from carbon build up, then the switch needed to be replaced. An eraser should be all that is needed to clean any "cleanable" contacts, any fine sand paper or emery cloth will make it worse by removing some of the contact surface. In one of your posts you mentioned cycling the ignition switch and the vehicle ran good, I would check the electrical part of your ignition switch again. The symptoms you have described could definitely just be a bad battery and ignition switch (electrical part). Good luck with it.

 

[Pags]

Tha is for the tip! I used a polishing wheel on my dremel to clean them. I do remember slight pitting on some of them as well. I'll definitely take your advice and replace it as soon as I get the car back from the body shop. I'd rather do that than spend un needed $$ on a new pcm and tune lol

 

[LLC5]

Tha is for the tip! I used a polishing wheel on my dremel to clean them. I do remember slight pitting on some of them as well. I'll definitely take your advice and replace it as soon as I get the car back from the body shop. I'd rather do that than spend un needed $$ on a new pcm and tune lol

Sorry to hear about your towing debacle. That is one dumb-ass towing company. Was it AAA by chance?

 

[dadaroo]

If you decide to go the route of a PCM swap it is easy to get the PCM for 2001 and I have the FSM also. With the 1998 FSM I could verify the pin outs for you.

 

[Pags]

@ LLC5, no it wasn't AAA, it was a towing company hired by my insurance company's roadside assistance. M&,M towing. @dadaroo, if the new ignition switch doesn't help, I'm for sure doing the swap. I'll call the dealer to see if I can get the 98 fsm.

 

[dadaroo]

I recommend you get one on eBay. New or good used there would be much cheaper.

 

[Pags]

Figured I'd throw an update out there while in sitting at the airport twiddling my thumbs.... My car is still at the shop, parts took a while to get in, paint took even longer. getting a new front bumper, quarter panels, bumper gaurds, and some other little things. But I should have it back soon. I picked up a new ignition switch to throw in when I get it back, still holding on to hope that it's a voltage issue and not the pcm that took a dump. Other than that there's not much else going on, was planning on seeing "the interview" but that's not gonna happen now lol guess I'll stick with Watching Team America for now!

 

[Pags]

So I figured out that if I disconnect the #7, or 8 injector( only 2 I've tried) the pcm has comm again. I did this multiple times. Plugged then back in, no comm from the pcm, unplugged them, pcm working fine again. What does that mean??

98 C5; 701rwhp, America! F**k Yea

 

[dadaroo]

It would appear that the injectors or the wiring is causing this issue. I would swap another injector into those locations and see what happens. Leave the questionable injectors off or unplugged when you do this.

 

[Pags]

It does this for all the injectors. So I'm guessing that a wire somewhere in the harness is causing some sort of short or something somewhere. Is there a single ground wire that ties into all of the injectors? Pcm kicks back on as soon as any 1 of the injectors is disconnected. The ignition switch is brand new too btw.

98 C5; 701rwhp, America! F**k Yea

 

[dadaroo]

Wow, that is weird. Power to the injectors is provided by relay 42. This feeds two fuses 18 an 22 with each one serving a bank of injectors. These fuses provide power to the injectors at all times when the engine is ON or in START. The PCM internally grounds each injector as required. Each injector has it's own wire going into the PCM for grounding.

I am at a loss right now as to how having all ground wires connected causes PCM No Comm and removing any one ground wire eliminates the No Comm issue.

If you disconnect one injector to eliminate the No Comm issue will the engine run?

 

[Pags]

I'm not sure about it running, never tried to fire it up when I had an injector disconnected. The Vette garage I brought the car to has a 98 pcm they're going to swap with mine to see if the pcm is causing the issue. Already replaced the relays with new ones just in case. Didn't help. If it is the pcm though I think I'm gonna save up the money for a FAST pcm to swap in, and bypass everything else I dont need to drive. I want to do some road trips once I get this sorted out, but don't want to run a speed density tune and chance ruining the engine. I guess the stock pcm can't handle the amount of mods to run the maf.

98 C5; 701rwhp, America! F**k Yea