Pin L of the red connector goes to pin 32 of the PCM connector. But what pin of the red or gray connector goes to fuse 16??. And yes pin 3 of the PCM connector is getting 12V and pins 11 & 12 are connected to battery ground.

 

If the rest of the cluster is working, it's getting 12V.

It's a dark blue/white wire, on pin A of the red and pin K of the grey connector. Which one feeds the MIL itself? Dunno, too lazy to trace the PCB.

And you haven't stated if it's tach or none; the wiring's different between the two PCBs. (The only wiring between the connectors on tach/none is the presence, or absence, on the red connector of two wires, one for the tach signal and one for the 12V to run the tach.)

RwP

 

I just found this wiring diagram. If its correct it seems to indicate f16 connects to pin k of the gray connector. We have already said that pin 32 of PCM connector goes to pin L of the red connector. So if i pull the cluster panel out and put 12V on pin k of gray and battery ground on pin L of red then the CEL should light. If it does light then i need to check the wire feeds to pins L and K to see which one is not working. Im not near my vehicle now so i cant check to see if there is a tach.

 

Well i finally got the CEL to work by grounding pin 32 with the ignition in Run. However, could not get it to light with just a lamp test. But i still couldn't get the light to flash error codes so i assume the PCM is bad. The notorious splice looks intact. There is a tachometer. I have run out of ideas except to find a new PCM. That web site you gave me looks promising. I really appreciate the help you have given me Ralph. This is my first time using a forum. For what its worth i give you an A+ for your help. Thanks again.
Louis

 

BTW, with the instrument panel out i traced the connections to the CEL. They are both on the red connector. Pin 32 goes to pin L and 12V comes in on pin K. The CEL was not working when grounding pin 32 because the red connector was poping off for some reason. But, with the red connector firmly in place, like i said the CEL comes on now when grounding pin 32 with the ign sw in Run but still does not come on for lamp test. Also with everything connected it does not flash error codes after cycling the ign sw 3 times. Just FYI.

 

Just installed a PCM I purchased online. The CEL works perfectly now. The lamp test works and the error codes flash on the CEL. Only 12 and 55 are displayed but it works. However, the engine cranks but still does not start. I put a pressure gauge on the fuel rail and it displayed about 40 psi while cranking. I connected a spark tester between the ignition coil and the cable going to the center of the distributer and there was no spark. I wanted to get your advice on how to proceed with testing because i don't want to damage the new PCM. From what I've read the cable going to the ignition coil should have 12V on one wire and a pulsed ground from the PCM on the other. It was suggested that the pulsed ground be tested with an LED test light so as not to damage the PCM. Please advise how i should proceed to find out why there is no spark. Thanks. Louis

 

Verify there's 12V on the coil while cranking, or by bypassing the Auto Shut Down relay in the Power Distribution Center.

You can NOID the coil, on the PCM side, to see if it's getting the signal.

RwP

 

You suggested using a noid light to test the signal from the PCM. Does the ignition coil have to be connected while running that test? Is the PCM just grounding pin 19 to produce that signal? The schematic I have shows the gray wire to the ignition coil connected to pin 57 of the PCM (asd B+) and also pin D of the asd relay. If i disconnect the PCM connector and put 12V on pin 57 and tap pin 19 with a grounded test light , will the coil produce spark if its good? Please explain what pin 57 does anyway. Thanks. Louis

 

Sorry not the gray wire but the DG/OR wire connects to pin 57 of the PCM and pin D of the asd relay.

 

Pin 57 of the PCM - in older trucks, that was ASD Sense; it told the ECU that the ASD was on.

I don't know why they call it BAT+ now; it still senses the ASD is on. There may be internal circuits that are powered off the ASD, though; that would explain the nomen change.

I'd put the NOID light across the coil; you can disconnect the coil if you wish, but that's more work than I want to do myself Then again, on the LA, it's a bit more effort (but not much more!) than it is on the Magnum.

I'd just bypass the ASD in the PDC; it's easy to do with a pair of 1/4" fast on style male connectors and a hank of 14GA or larger wire (say about 4" to make a nice loop up and down). They also sell relay replacements; it's a mechanical switch you can hand toggle to force the output ON or OFF without any concern for what the ECU is doing or not.

RwP