Crank sensor problems w/ 411 conversion on LT1

[mekkis]

Hey everyone, trying to help out a guy with a no start problem.

1997 Z28
24X EFI Connection setup w/ cam sync distributor
Guy goes to fire it for the first time, fuel pump primes and will talk to a scantool, but:

- No RPM signal (and no fuel or fire)
- wave a wrench in front of the crank sensor and nothing
- plug and unplug the sensor w/ ignition on and it sees a blip

Either have a bad crank sensor or a wiring problem, obviously. Guy says the crank sensor pin out is correct - but I am wondering if he has looking into connector and looking at back of connector orientation mixed up. Can anyone verify how it is supposed to be pinned for this conversion, or for the black box ECU era 7.4 trucks where the sensor is sourced from? I'd like to rule that out before throwing crank sensors at it in case the wiring would hurt the sensor.

Thanks!

[Aksl]

Hello mekkis,

I as well have an LT1 small block but on a truck, with 0411 conversion.

Ok, i gues your friend there got no spark, is that right?
So there are only 3 wires at the crank sensor: Pink is + voltage, PPL CKP Sensor Low Reference (-) that goes to pin 21 of C1 Blue connector of the 411, and the YEL CKP Sensor Signal that goes to pin 12 of C1 Blue connector of 411.

In my case the problem was in the pins of the PCM/ECM connector, the pins were old and had poor contact, so i had to cut the old pins and repin the connectors.

The Sensor itself you can easyly check, with a diod light, connecting the diod connector to + and the sensor signal, turning the ignition, the diod light should blink.

What the sensor signal does if sends variable signal, plus/minus, to the PCM/ECM. Than the PCM/ECM sends the signal to the ignition coil from Blue C1 pin-73 CMP Sensor Signal.

Hope that helps.

[Fast355]

Hello mekkis,

I as well have an LT1 small block but on a truck, with 0411 conversion.

Ok, i gues your friend there got no spark, is that right?
So there are only 3 wires at the crank sensor: Pink is + voltage, PPL CKP Sensor Low Reference (-) that goes to pin 21 of C1 Blue connector of the 411, and the YEL CKP Sensor Signal that goes to pin 12 of C1 Blue connector of 411.

In my case the problem was in the pins of the PCM/ECM connector, the pins were old and had poor contact, so i had to cut the old pins and repin the connectors.

The Sensor itself you can easyly check, with a diod light, connecting the diod connector to + and the sensor signal, turning the ignition, the diod light should blink.

What the sensor signal does if sends variable signal, plus/minus, to the PCM/ECM. Than the PCM/ECM sends the signal to the ignition coil from Blue C1 pin-73 CMP Sensor Signal.

Hope that helps.

24X uses 8 ignition coils

From what I remember on my 24x swap, the crank sensor pigtail has to be repined to work correctly with the sensor provided. It has been a long time since I did mine but I seem to remember it being the center pin and one outer pin being swapped.

[lionelhutz]

Factory 96-97 LT1 wiring of the sensor is,
A - pink - 12V
B - pink/black - OPTI reference low = ground
C - yellow - sensor output

The LS1 sensor wiring is;
A - blue/white - output
B - yellow/black - low reference
C - green - 12V reference

So, A and C are reversed between the 2 sensors.