I'm not good with 3rd Gen. Built some 1st Gens. Got an 87 IROC convertible with a whole bunch of rare options a few years ago and recently while Craig's listing for parts I found T-top car with ALL THE SAME exact options. So instead of parting it out I've decided to get it running. Here's the story. It's been sitting under a giant redwood tree in 8 inches of mud in the Santa Cruz mountains for the last 10 years. But the entire car is there and other than typical replacement parts it is all original. The gal even had the window sticker. (Weird woman like something out of the movie Deliverance.)

Santa Cruz Mts are a very humid place. There's no body rust but pretty much all the electrical contacts are corroded. I've been going through and cleaning as much of the electrical as I can get to. Haven't got to it all yet. I've verified that fuel pumps kicks in when I jump the ALDL terminal G. I've replaced the pick up coil, ignition module, cap rotor and coil, plugs and wires. Still no spark. The headlights work, the door chime works and the drivers window powers up and down very slowly. NONE of the instrument panel works at all. No lights, no HVAC controls nothing. So i know there's still electrical issues somewhere.

I'll chase the little things down later. but I promised my wife that I'd get this thing running pronto as a condition of dragging it home and parking in the drive. I suspect there are ECM or ground connection problems. The only ground I haven't go to yet is in fact the ECM ground on the back of the passenger side head.

But why no instrument panel lights? How to test for IP power? All fuses in fuse block replaced and fuse block cleaned

Do I need ECM powered to achieve spark? ( i know i need it to run but one thing at a time)

How to test for ECM power?

Help me save this car!! Thanks

 

I would get a manual with a good wiring diagram and start from the battery. Test the battery cables resistance and voltage drop and move on as you get it to flow power. Corrosion can wick up battery cables, often the negative cable. You can't see it under the insulation.

 

Are you sure you're injectors are working? If it's been sitting that long, chances are those are gone. I would replace that ECM, simply due to it sitting so long. You might be able to check power by putting a voltmeter at the ALDL serial port and ground (looking for 5V I believe). If you get no power, it could just be that wire has a break somewhere, though. I don't have your ECM, but do a google search for a pinout of it, find the power to the ECM and put a volt meter on the connector side. Also, you might want to check the grounds in the engine bay and make sure those aren't corroded. If you ground to the heads or block is corroded, you'll need to replace the grounding strap(s) or try to remove that corrosion.

For the inst. panel, that's more than likely a grounding issue as well. Start taking it apart and look for corroded wires or grounds. I know you've started doing this, but I don't know how far you've gotten with it. Good luck and keep us posted.

 

Good advice, but replacing the ECM may not be necessary. All boards in the ECM are coated, and the chances are even-money that the "replacement" ECM is just as old, and wasn't stored any better.

The distributor needs 12V at the BAT terminal. Just for diagnosis, disconnect the EST bypass connector along the firewall.

If, as Ransford suggests, the regulated 5V power supply from the ECM is present, the ECM is getting power. It's probably easiest to check the 5VDC supply at the ALDL or TPS gray wire. If the fuel pump is not running and the ECM seems dead, check the 20A fuse near the battery.

 

OK, i have replaced essentially everything in the ignition system except the ECM. I took it all from my other car which I know worked perfect. Now I am on to fuel delivery issues. Here's what I have done. Verified the pump and relay work.

1. Checked 20a fuse for pump and ECM near battery negative
2. Jumped ALDL pin G and pump primes
3. Put a gage on the fuel rail while doing an ALDL pin jump and got 43psi. So pump works
4. Got 12 volts at large orange wire at FPR plus verified ground at FPR
5. Got test light positive in key on at FPR control power
6. Jumped large orange to large tan/white at FPR and got no prime.
7. Also new oil pressure switch

I get the 2 second control switch for prime but that signal does not seem to be making it way to the pump. Is that an ECM issue or maybe C313 issue?

Here's what I have not done yet.

1. Checked C313 connector near gas tank -UPDATE: OK JUST APPLIED 12V TO TAN AND GROUND TO BLACK AND PUMP RAN GREAT!
2. Swapped ECM

Any thoughts? Anybody?

EDIT: DOES THIS CIRCUIT HAVE TO RUN THRU THE ECM SOME WHERE? SO WHAT I AM ASKING HERE IS THIS. I KNOW THE RELAY GETS THE PRIME SIGNAL FROM THE KEY ON, I KNOW THE PUMP IS GOOD. THE PRIME SIGNAL IS GETTING LOST SOMEWHERE BETWEEN THE RELAY AND THE PUMP. I KNOW THIS BECAUSE I PUT A TEST LIGHT AT THE C313 SUPPLY SIDE AND GOT NOTHING BUT WHEN I BYPASSED THE SUPPLY SIDE AND HOT WIRED 12V DIRECTLY TO THE PUMP SIDE OF C313 THE PUMP RAN GREAT. DOES THE PRIME SIGNAL GO TO THE RELAY AND THEN BACK TO THE ECM OR SOMEWHERE ELSE (WHERE IT IS GETTING LOST) AND THEN ON TO THE C313 AND PUMP? IF SO IS IT GOING TO THE ECM? THAT IS THE ONLY THING I HAVE NOT ELIMINATED YET.

EDIT: I JUST CONNECTED A TEST LIGHT TO THE SUPPLY SIDE OF THE C313 AND GOT A 2 SECOND HOT. SO THAT BLOWS MY THOUGHTS THAT THE PRIME SIGNAL IS NOT GETTING TO THE PUMP. NOW I KNOW THE PUMP IS PRIMING AND THE FUEL IS GETTING TO THE RAIL BECAUSE I TESTED IT AT 43 PSI. JUST CRANKED IT 3 TIMES FOR 20 SECONDS AND THEN QUICKLY PULLED TWO PLUGS. BOTH BONE DRY. EITHER NO INJECTOR PULSE OR MAYBE BAD FUEL REGULATOR? HELP!

My god this is maddening! I didnt pull all plugs cuz you all know how fun that is but the 2 i did pull were bone dry. So now I'm thinking FP regulator. But just for giggles i finally swapped the ecm for one that i know works. nothing! so then I'm thinking must be injector pulse so i slap on a NOID light to #1. nothing. Move the NOID light to #3 and while cranking that damn thing snorts for a second. put the injector connector back on thinking I might be in business and start cranking. nothing!! UGH!!

 

If it is performing the 2-second prime cycle, the ECM is doing its job. If the ECM is closing the pump relay while the engine is running, the ECM is doing its job.

If you jumpered a 12V source around the relay and the engine ran properly, I'd suspect the relay, the wiring around the relay, of the 12V source wiring to the relay.

 

From your previous post, it would seem that correct fuel pressure of 43 PSIG has been established. The pump should run the 2-second prime upon ignition-on, and also while cranking. If that is the case, move on to the injectors.

If you are certain the injector test light is working, there may be a problem with the wiring between the injector harness at the engine and the ECM. That involves a connector inside the vehicle (C221), two fuses in the interior fuse panel, and the connectors at the ECM. Since you have already swapped the ECM, it's likely that un-seating and re-seating the the connectors has wiped the contacts in the ECM connectors clean.

Verify by voltmeter that each bank of injectors has the necessary 12VDC supply on the pink/black wires when the ignition is on. If the voltage is missing, check the INJ fuses in the interior fuse panel. If voltage is present at BOTH ends of BOTH fuses, check the connections in the C221 connector. It is a 6-contact black plastic connector arranged in two rows of three pins/sockets.

If the voltage is present at the injectors, inspect the return ground connections between the injectors and the ECM. These pass through the cowl wire harness to the ECM.

 

If the voltage is present at the injectors, inspect the return ground connections between the injectors and the ECM. These pass through the cowl wire harness to the ECM.[/QUOTE]

FIRST: Where is C221 located?

I've got 12v on ONE SIDE ONLY of each fuse and then of course because of this there is NOT 12 volts on either side of the injectors. BUT the car has snorted twice at the least expected times. This intermittence has me baffled. The last time it snorted was when I was NOID testing Inj #3. I've read that a bad injector will shut down the whole bank. So perhaps when I unplugged #3 to put the NOID on it and it snorted maybe that indicates a bad Inj #3 cuz at that point it wasn't in the circuit any longer? What else would cause 12v on one side of each fuse but not the other?

Also, I just checked ECM connector pins and pin D15 for injectors 1357 have 12 volts with key on, but pin D16 for injectors 2468 has almost nothing. Gotta be an open in this somewhere? Obviously this open circuit is the reason I have no power on one side of each fuse and no 12 volts on either side of the injectors. Where do I hunt this down? I suck at reading wiring schematics but will give that a go. Feels like I'm getting close! Thanks for everyone's help

 

If there is 12V on only one side of a given fuse (nothing on the other) the fuse has probably failed.

The ECM does not switch positive voltage to the injectors - It switches the injectors to ground to complete the circuits to fire them.. Reading 12V at the ECM injector control terminals is not an indication of ECM nor injector failure. We would have to know the state of the injector driver circuits to diagnose an ECM problem and since you apparently do not have power from the injector fuses, the rest is almost irrelevant at this point.

 

Ya I've learned that the injectors are always (key on) at 12 v and the ECM triggers a ground to pulse them? Correct? but i dont have 12 volts at any injector (ever). I do have 12 volts at power side of each of the 2 fuses. any idea why that 12 v is not making it from fuse to injector? where does that circuit go after leaving the fuse block. As stated above I DO have 12 v at D15 but not D16.

I have all along thought this is a ground problem. I've hit all grounds that I know of except ONE and that is the ground on the passenger side head which happens to be the ecm ground. I also have zero instrument panel power. everything else seems to work except for injectors and IP. I cant get to that pass side head ground without dismantling half that side of the motor so I've left it for last even tho it was my first suspect. Thoughts?

This is starting to become the Davinci Code!

 

The 12V should be present on BOTH ends of the fuse. If not, get new fuses.

 

Pics................

 

SOLVED!! I started another thread regarding not getting any voltage to the injectors. Suggestions in that thread lead me to dig into the wiring a lot deeper. I had intermittent voltage to injectors, voltage would drop to zero at the coil while cranking and I had no instrument panel power and no power to the rear hatch lid. Sometimes with the key in run I would get voltage and sometimes not. Can anybody guess what it was?

It was the friggin ignition switch. Bad or intermittent ignition switch. ALL of these things are dependent upon that switch to work in RUN position and the coil of course needs voltage while cranking. The key switch was hit and miss. Looking back it seems it should have been so easy and obvious but it never is. Thank you all for you help