7.4 CKP sensor
A = 12v
B = lo ref
C = signal
LS CKP sensor
A = signal
B = lo ref
C = 12v
7.4 CKP sensor
A = 12v
B = lo ref
C = signal
LS CKP sensor
A = signal
B = lo ref
C = 12v
Originally Posted by SiriusC1024
My pigtail is the left style.
IMG_2645.jpg
Let me qualify this. They match the AllData 5 page color drawing they supply.
2001 C2500 2WD 6.0L VIN U
Drawing seems nice unless they labeled the low ref wrong.
Which sensor is it?
7.4 1998 in the dizzy.
New CMP sensor and about the same.
I did find a short between two pins of the CMP sensor, zero resistance.
Sending juice right back into the PCM I would imagine.??
So I totally changed the fuel to stock 6.0L numbers and she stayed running longer.
The code for A on the CMP didn't appear on the latest log.
Funny, no O2 codes came up even though I don't have any hooked up.
They will be arriving Wednesday. I better stop playing until I got those installed, wired, and monitoring things.
Thanks you.
CKP. Crankshaft.
CMP. Camshaft.
Got it, thanks.
Cam sensor changed today.
I'm asking, because the two crank position sensors have different pinning, and mis-wired at either CMP or CKP can take down the 12vref for the other one. The original 1998 7.4 wasn't like that, the 12vrefs didn't come from the PCM they came from fuses.
You've been messin' with both of them what seems like randomly without being real clear about what you have and so makes it hard to nail down whether you have any wires crossed or not.
I have the 7.4 crank sensor.
I had to swap the wires around from the 01 pin outs to get it to fire as they were as you mentioned, where, when I plugged in the cam sensor, 1.26 volts instead of 12V was at the crank sensor.
So, 7.4 CKP is wired:
A is 12Volts from PCM, C1-2,
B is Low ref, C1-21,
C is signal, C1-12
I have a C6 Vette MAF/IAT combo sensor also.
Actually, no, I don't. It's not the same as what's listed on Rock Auto at all.
I will have to find out what it's from.
It uses the same pigtail as the Vortec CMP sensor.
I assumed only, because I wondered, what other sensor is going to fit this cover.
Well, how about that. It's from a 2000 Chevrolet C7500 Kodiak. I'm sure there are all kind of wiring diagrams floating around for this, ha.....
Because the fellers that started selling the kit discovered the 24X reluctor on this motor and the light bulb went off for them.
I remembered this story is what got me to track it down. Big 5 ton truck or something.
2000 medium duty truck 7.4L
screenshot.12-05-2025 19.50.00.png screenshot.12-05-2025 19.48.01.jpg
edit: Now I don't know and am not going to go look up if that uses the same PCM as a 6.0L LD truck, so don't use those references on the PCM side as anything but '12vref goes to this pin at the sensor' type stuff.
Last edited by blindsquirrel; 05-12-2025 at 08:03 PM.
Thanks. Only problem is I have no clue how to read the symbols, ha.......
I'll search for that I guess.
Thanks.
I couldn't find those.
From left to right on each looks like 12v, signal, ground.
The ground symbol in the PCM should be easily identifiable, the clue to which is the signal is up in the picture of the sensor(s), so there's only one thing the third one can be.
Thanks.
I'm certain the wires are fine.
I gotta get the new O2's installed next and do some scanning.
Then, make some changes to the tune so that it will stay running?
It ran about 30 seconds today without touching the throttle.
Good sign.
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