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Discussion Starter #1
in my 1997 mustang gt body I swapped in 1996 GT engine. I took all of spring break getting it done and now the car cranks fine, I can hear the fuel pump wining, with key off the CEL comes on, everything seems normal to me, except it just cranks and won't start.

There's no power at the ignition coils and I can't seem to find a decent wiring diagram or anything to help me diagnose it. What things should I check when there's no power at the coil? there's power at the fuse box and obviously the starter and everything. Could it be a computer related issue?

Any help would be appreciated, even a quick rundown on how power flows to the plugs on this car or an electrical diagram.

Thanks!
 

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Have you CONFIRMED there is key on power INTO and out of the I/P #18 fuse?

Did you install the ground strap from the left hand motor mount to the frame rail?

There'a a large square connector (C104) in the engine bay. It would have been disconnected during the swap. Double check that it's fully seated.

If interested in getting a full set of service manuals and wiring diagrams I may be able to help. PM if interested.
 

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Is there no power at all on the cable going to the distributor? If so, try follow the cable by hand and see if it is properly hooked up to the battery. Also double check all the other wiring in the engine bay, could be as easy as a loose connector. I don't have any experience with the distributor system used on those model year Mustangs, but checking the basics is always important nevertheless.
 

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Discussion Starter #4
My year doesn't have distributors it's an ignition coil system. Idk exactly where the wires going into te cable come from, just that there's confirmed no power to them so somewhere between the battery and the coil it's losing it, maybe in the computer idk.

I checked for power in all the fuses I the under good fuse box and they all had power, is that where the fuse 18 is located?

I've triple checked the ground strap to the engine, I cleaned it off with a wire brush and electrical cleaner and such.

Where is this square connector?

I'd love an ignition wiring diagram it'd be incredibly helpful, ill pm you.
 

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Discussion Starter #5
After doing some more testing and using a different scan program that actually had a scope i learned a bit more. Turns out it does have voltage at the coil I just couldn't see it because it's only briefly.

Watching the scope everything looks normal for the first few milliseconds, when I first crank it the spark timing advances, it builds voltage, it acts like it's going to go on the scope, then it suddenly loses crankshaft/camshaft position signal and shortly after everything else drops off. So basically I need to figure out why it's losing crank/cam position signal.

So once i get a chance to get back into the garage i'll check all the wires going into them and everthing, unless anyone has other ideas. That may not be today though, turns out there's snow on the ground again. We'll see.
 

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Discussion Starter #6
Oh, and wmburns, I figured out that the c104 is the 42 pin computer connector. I triple checked that and even tried swapping the 96 PCM in from the other car. No difference.
 

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FWIIW, there should ALWAYS be +12 volts to the coil pack R/LG power wire. If the voltage drops out, STOP and find out why. A bad CKP sensor will not make the R/LG voltage drop in/out.

Testing at the signal return lines is another matter. Remember the system is a ground start system. So it would be expected if testing the signal return lines to see the voltage shift as the PCM "fires" the circuit.

IF the CKP signal is dropping that would cause the spark to come and go. IMO the easiest way to test the CKP sensor is with an ODB2 scanner. Monitor RPM's while cranking. IF the RPM's change, the CKP is working.

My Ford manual says C104 is in the engine bay. I mentioned this connector because it's a connector that would be disconnected during a motor swap. The PCM connector is C294 for the 96 MY.

Have you double checked the grounds around the radiator core support? Are they clean and tight?

There is a black wire with a white strip. It's connects to a single pin connector located near the battery. This is the PCM and CCRM ground. Double check that it is connected. This is a connector that would have been removed during the motor swap.

Here's some more information in a crank with no start check list.

http://www.allfordmustangs.com/forums/4-6l-tech/336452-1997-mustang-wont-ignite.html#2984838
 
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