OK Guys, this post will probably make you laugh and maybe even realize that "your" problems aren't that bad : )
If there's anyone out there that can help, I'd be the most grateful member here.
Here goes...
I'm putting a 1991 L98 w/700R4 (from a crashed vette) into a 53 Chevy truck (suspension too but that's no problem). I am using the entire wiring harness, steering column, fuel pump and gauges from the car too. Just about all the mock-up work is done so I figured it was time to make some noise with an engine run. (Note, the car ran & drove the day I started taking it apart). This is where the problem comes in... I have all the plugs from the harness plugged in, all the grounds grounded, have a good battery hooked up, and have the right key. Issues as far as I can tell now...
Orange "SECURITY" light flashes on lower left of gauge cluster all the time.
Nothing happens when I turn the key, not even lights on gauges (unless headlight switch is on).
With the key in the on position & headlight switch "on", the center of the digital readout lights up and shows "SYS" for a couple of seconds.
No clicking anywhere, not even fuel pump.
When I turn the headlight switch I get a beeping tone like a warning that lights are on.
Another observation I made after watching a video I made of a start-up before I started disassembling... The tach, while not running before taking it apart was resting at zero (or the beginning of the scale). Now, the tach rests at around 5500.
Seems like something somewhere is not getting juice. Has anyone been there and done that?
Thanks in advance, Ken

 

The VATS security system is likely keeping your engine from starting & running.
You need to connect it correctly(troubleshoot the problem((s)) or Disable it.

You need the Tachometer filter connected inline with the TACH wire going back to the instrument cluster.
Tach should read at "0" again at rest with Key On , Engine Off.

BR

 

If he has the original column and key installed then VATS should still be working like it did when car came apart

Did you install the '91 CCM ?

You may have problems elsewhere with your wiring .Gauge operation is independent from ECM operation

Fuel pump operation is independent of above mentioned VATS and should run for 2 sec ; key on

 

Hi BR & RODJ,
BR - all the wires that were connected before the tach was removed are now hooked back up. In the scheme of things I don't think this is my first problem. Somehow the system is not getting initial 12v juice.
Yes, I have the column and all other electrical components from the 91 C4. I think my problem is before the tach and the VATS as I don't get anything when I turn the key. I've tried pulling codes with the trip computer panel but nothing there. There has to be something I've missed but I have every plug, ground and module in place. ???

Thanks for the thoughts. I'm still smiling but the hair pulling is on its way : ) If you have any thoughts on tricking the system by jumping in power, I'm all ears.

 

You might talk to the guys at Street & Performance - www.hotrodlane.cc - they do a lot a crazy conversions.

 

A FSM for the electrical schematic would be a great help to you right now & a digital DVM / AC-DC, OHM Multimeter.

Check all fusible links if you retained them in the underhood wiring harness from the C4 donar car.

BR

 

"How" crashed was this ´91?
Reason I´m asking is the airbag in the wheel, did it deploy or not.
If it did, the DERM/CCM might be fried.

 

Hi Vette079,
The car had a light hit on the right side door. Not that bad at all and the air-bag did not blow. The hit caused the car to kind of split open underneath so it was a total. What is the DERM/CCM? I will check anything at this point. Does the yellow harness for the airbag system have to be plugged in? Remember, this car ran and drove the day I took it apart. Thanks.

 

Yes if you have retained all the stock setup.

CCM
Alum unit that was behind radio




DERM is orange box that was buried under console and had yellow wiring attached

 

Hello Everyone.
Update on research & testing.
I found this thread on ASK.com

http://www.justanswer.com/chevy/3awg...nvertible.html

The information here has lead me to the ABS harness plug that is dangling because I no longer have the pump/valve module. This thread says that the grey/red wire in the plug should show 5v. My grey/red wire has zero volts. I have another wire (orange) in this plug that has 12v. So, I'm thinking that the electronics in the ABS (EBCM) pump/valve somehow converts that 12v down to 5v and sends it back to the CCM or ECM which in turn tells them they can fire up all the systems to let the car start.
Does this sound feasible or am I telling myself a fairy tale? If yes (feasible ), does anyone know of a way I can make 5v and deliver it to this grey/red wire? Or??
Thanks again for taking time to roll this through your heads and give feedback.

 

I have an update and questions.

Update; After a couple of months of not working on the project, mostly because of frustration, I'm back on it. After a few hours of meticulous searching I found a couple of bad wire connections in plugs at steering column (loosened from all the moving around). Fixed them.
Now... Turn key to "on", gauges light up as normal but no fuel pump noise, turn the key to "start" and it cranks but no start ( I've cranked for several seconds and "do" have oil pressure). I jumped the fuel pump and have pressure in the rail at Schroder valve. Turn key, cranks but still no start. I checked a sparkplug and found that i have spark so I tried a squirt bottle with gas shooting into intake & it runs!! No gas from squirt bottle, it stops running.
Now that the gauges light up I'm able to get some codes. Jump ALDL "A" to "G" module 1 (CCM), I get C41, C72 & C74 as well as the same codes in H (History). When it goes to Module 4 (ECM) I get "Err" (error). I've done a bunch of looking around to learn how to diagnose this problem but all I can find is what the problem actually is. It is telling me that the ECM cannot communicate with the CCM" If the CCM cannot communicate with the other computers, the letters "ERR" will show up on the display." Everything seems to be plugged in properly.
Seems like the computer is not telling the fuel pump to run when the key goes to "on" and then even with pressure in the rails the computer is not telling the injectors to pulse.

Questions; Can an ECM go bad just sitting? How about the PROM? (I don't have another one to test with)
Any good ideas?

Thanks in advance!!

 

The ECM turns on the fuel pump when it sees reference pulses from the ignition module in the distributor. These pulses are generated any time the engine is turning (cranking or running). The fact that it runs with hand-injected fuel says that part is OK.

The ECM turns on the fuel pump through a fuel pump relay. There is also an oil pressure switch on the back of the engine (two wires) that is in parallel with the fuel pump relay. It is supposed to take over if the relay fails. It turns on with about 4 PSI (I don't recall the exact pressure), so it should kick in after cranking a bit. It sure sounds like your fuel pump isn't getting any power (or maybe a ground). Are you running the stock Corvette style fuel pump in the tank or some other configuration?

 

Hi Cliff,
Thank you for taking time to think about this and post.
Yes, I am using the exact in-tank fuel pump along with the harness' from the 91 Vette. I'll try to find and trace the wire that feeds the fuel pump right out of the ECM. I've checked at the "FP" fuse and don't have power. I can jump it the pump from the fuse location though.

Remember, I still don't have injectors functioning either. I have pressure in the rails after jumping fuel pump, so if the injectors were working it would run. A local Pal suggested I try it with the pump jumped and turning when I try to start engine, I haven't done that yet but I will today.

 

Sounds like the fusible link that supplies power to ECM and Fuel pump. It is near the gaggle of others by the battery and there is a long black funky connector just after it (is used to clear ECM without disconnecting battery). If no power at fuel pump fuse this is next in line.

 

I had checked those fuses a while ago but it's a good idea to hit them again. They're kind of a dumb setup, you have to chop and splice if they go bad.
Heading out to the shop now. I'll let you know.

Thanks for the idea,

KG

 

OK, some new things...
All grounds "seem" to be fine. All fusible links show 12v downstream.

I checked the voltage at the ecm fuse in the fuse box (pink/black wire), zero with key off & only .41 with key on. I followed the wire to the ecm and also looked on a pin-out sheet, B10 is the location on the ecm, .41 volts there too.

Can I jump 12v in at the fuse or am I asking to melt something?

 

You will NOT believe this...
I followed the other side of the ecm fuse wire ( first side, Pink/black goes to ecm at B10) the other side is yellow and goes to the all yellow plugs harness which I did not have plugged in. Plugged it in and turned the key to "on", fuel pump runs, turned it to "start", ENGINE STARTED!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Now on to a few months of fab & bodywork.
I'll keep you posted.

Thank you all VERY much for bouncing ideas around. I'll be happy to help anyone doing a frankin-swap