95 850 No Crank After M56 Swap

Post by **polskamafia mjl** » 15 Jun 2015, 18:25

Hello again.

I'm back with yet another problem. After completing the M56 swap I tried to build oil pressure with the fuel pump relay removed (103 under the fuse box cover). Turning the key forward results in some clicking and nothing else.

The PNP harness is temporarily plugged into the PNP switch. I have the switch rotated to park (which I believe is all the way to the right). I tried cranking with the switch set to neutral but no dice.

Its possible the connectors for the O2 sensors are backwards. As far as I know that won't keep the engine from cranking but I thought I would throw that in here.

This is a 95 and I believe the M56 transmission I got was off of a 94. The flywheel I got is presumably from the same car. As I understand it, using a 95 or earlier flywheel does not require reversing polarity on the crank sensor. So I didn't reverse it. From the diagram below it looks the flex plate off of the auto and flywheel from the manual both use the old style of holes for the crank sensor (flywheel 'A') so I'm pretty sure I don't need to mess with that wiring.

: Old vs Newer Style Flywheels

The flywheel for the M56 has holes in it as you can see.

: M56 Flywheel w/ holes; clutch_presure plate.JPG (125.51 KiB) Viewed 1613 times

And the flex plate from the Aw50-40.

: Flexplate from slushbox

Now admittedly the flexplate has square holes while the fly wheel has round ones. Is that enough of a difference to require switching the polarity?

One final item I would like to know about is the wiring for the starter. I'm fairly confident I connected everything correctly but if anyone has a good image of that wiring I would love to see it.

As always thanks a lot for your time!

EDIT: I forgot to mention I measured the battery voltage since it has been sitting for several weeks. It read 12.3 ~ 12.4 Volts. That should be more than enough to crank right?

Post by **Ozark Lee** » 15 Jun 2015, 19:29

12.3 or 12.4 is on the low side but it should crank. As I recall there are four wires associated with the starter. The battery cable, the alternator cable, the fan wire, and the small starter engage wire from the ignition. The latter is typically the small Green wire with a Red stripe. The three wires with the large terminals (Battery, Alternator & Fan) all go to the large lug on the solenoid that does not have the lead to the starter motor hooked up to it. The starter engage wire goes to the other small terminal on the solenoid by itself.

...Lee

Post by **polskamafia mjl** » 15 Jun 2015, 19:43

I'll double check the wiring for the starter tomorrow after work since its dark now and I'm a little burned out.

I unplugged the PNP switch and jumped pins 6 & 7 with a small length of wire and tried cranking. All I got was the same clicking as before which must be a relay or something I hope. With the length of wire removed and key turned forward there's no sound at all so I think I can eliminate the PNP connector as the problem.

What are the bare bones items that need to be present for the engine to crank? Cam, and crank sensor signals need to be present and correct and we need power to the starter, right? With those three things and the PNP plug jumped correctly the ECU will at least crank the engine, correct?

Post by **Ozark Lee** » 15 Jun 2015, 20:37

To crank it only needs battery to the solenoid and switched battery voltage to the solenoid coil terminal. Without the other sensors it won't fire but it will crank. I think your PNP test is a good one and it would indicate the PNP is in a position that should allow the car to crank and it takes the immobilizer out of the equation.

Do you have jumper cables?

...Lee

Post by **polskamafia mjl** » 15 Jun 2015, 22:01

I do have jumper cables but I'm not sure whether they are here or in my girl friend's car. She's visiting her dad so if they are in her car I won't physically have them until Friday I think. What did you have in mind?

A friend of mine suggested that the clicking I'm hearing when I turn the key may be the bendix on the starter.

He and I also tried bump starting the car to no avail. I don't know if these two items help shed light on the problem or not but again, I figured I may as well include them.

Post by **Ozark Lee** » 16 Jun 2015, 00:37

It could be that the battery is just to flat to get the car to crank. I would just jump it or put the battery on a charger to get it fully charged and try again. The 12ish volts may be dropping substantially when the load if the starter is applied.

...Lee

Post by **abscate** » 16 Jun 2015, 04:45

You've just got a flat battery. None of the sensors will affect cranking

Do you have the starter bypass wire near the left strut mount?

Post by **E Showell** » 16 Jun 2015, 08:54

I do remember recalling reading that you cannot push start the manual transmission version of these cars. I can't remember the reason for it, but believe it is some sort of additional safety feature.

Post by **abscate** » 16 Jun 2015, 08:57

IS that true? If you turn off your motor at speed, can't you restart it by putting it back in gear and clutch back in? I havent tried this but would be surprised if it didn't work.

It would be easy to program the ECU to not turn back on if the car is moving, though.

Post by **Ozark Lee** » 16 Jun 2015, 09:04

On my '94 you can roll it down the hill and pop the clutch to start it with no problem but I don't think that would be my preferred method on a maiden voyage.

There is no clutch / starter interrupt switch and neither the ECU or the starter ever knows if the clutch is engaged or not. My daughter more or less figured that out as she turned the key and about cranked the car through the garage door. She did have the pedal in but she is very short and she didn't have it in all the way.

...Lee