black w/red wire at ignition control module harness

[JiggaFan]

'93 lumina

3.1L V6

Federal Emission

 

isn't that the wire that's supposed to be switched to 12volts when the ignition is turned on?

 

my lumina is not starting...the engine is turning over, but not firing up. i've verified fuel at the fuel rails, changed spark plugs and wires, cleared the "service enging soon" codes (IAC, 02 sensore, and Coolant Temp sensor).

 

i'm guessing it's something electrical, now...

 

the haynes manual wire schemantics are right for this harness i've got...it's got a black w/red, tan w/black, purple w/white, and 2 white wires in the 6-pin harness (one hole is left blank).

 

but the haynes chapter on ignition says i should be getting 12volts at the "F" pin of the ICM harness. only problem is, the harness was labled "A-B-C-D-E-F" instead of "L-K-A-B-G-H" as in the haynes manual chapter 5 on Engine Electical systems.

 

well, this black w/red wire is switching from 0 volts key-off to 1.00 volt key-on. but when i reverse the DMM probes, i get -12.00+ volts (ground) key-off, then -11.00+ volts (ground again) key-on.

 

i'm thinking of cutting this wire from the harness and jumping it to the black w/red wire coming out of the ECM. i'm guessing that somehow, this wire is grounding out somewhere along its route from the ECM through the valley between the front of the engine and radiator up to the ICM.

 

anybody got a clue as to what i'm talking about?

[Tim]

Before you start cutting wires I'd check for a good signal from the crankshaft position sensor. Last time my 92 3.1 had crank-no start symptoms the CPS had failed. My guess is the CPS is more likely than a short in the wiring though not impossible. Also, your voltage measurements don't make a lot of sense...reversing the meter leads should just change the polarity of the reading and not have any impact on the value that is read.

Tim

[JiggaFan]

...Also, your voltage measurements don't make a lot of sense...reversing the meter leads should just change the polarity of the reading and not have any impact on the value that is read.

Tim

red probe on black w/red wire:

0.00 v key-off

1.00 v key-on

 

black probe on black w/red wire:

-12.50 v key-off

-11.50 v key-on

 

the black w/red wire is a much better source of ground than it is a source for 12v battery voltage.

 

CPS is only $17 at autozone. is it a biitch to change? gotta go hoisting the engine and what not? dropping tranny's and what not?

[GP1138]

...Also, your voltage measurements don't make a lot of sense...reversing the meter leads should just change the polarity of the reading and not have any impact on the value that is read.

Tim

red probe on black w/red wire:

0.00 v key-off

1.00 v key-on

 

black probe on black w/red wire:

-12.50 v key-off

-11.50 v key-on

 

the black w/red wire is a much better source of ground than it is a source for 12v battery voltage.

 

CPS is only $17 at autozone. is it a biitch to change? gotta go hoisting the engine and what not? dropping tranny's and what not?

 

No hoisting engine or dropping tranny. I believe you can get to it from below, I believe it is a bitch. If you roll the engine forward and squat down on top of it you might be able to reach behind if you're skinny like me.

[JiggaFan]

found this link in another "crank, won't start" post:

http://members.fortunecity.com/slade901/automobile/Ignition_Troubleshooting.htm

 

appears that the black w/red wire i'm referring to is a ground wire.

 

so there's no need in me cutting that wire and jumping it or anything...only wire i need to check for battery voltage at is the pink/black on the 2-pin harness on the driver's side of the ignition control module.

 

looks like i'll be running to my midnight-close autozone here shortly for a crankshaft position sensor.

[JiggaFan]

yet another victim of the notorious

 

Crankshaft Position Sensor

 

I replaced it and sure enough, that hoe fired right up.

 

$16.99 for the part.

 

Accessible from the bottom of the car behind the oil pan. I couldn't see it from the top. But I ended up having to lock a vise grip on it from the bottom, then pull up from the top to finish getting the destroyed CPS from the engine. It looked perfectly fine when I first spotted it. But my attempts to pry it out with a flat head screwdriver broke off the head a number of times. So I used a lock set of vise grips to grip the two metal leads and yanked it out from the top.