1999 V70 T5 M56 ELIZABETH No crank Problem [9472949 clutch switch ] Topic is solved

[callahanoffroad]

This makes me miss my old Landy Cruiser. You could hand crank the crankshaft with the key in run to start it. Logic circuit and wiring? Dang. Too much kerfuffle for me!

[abscate]

Well, here is the troubleshooting report

Car won’t crank in posIII

Jumping it at the bypass connector, car cranks and starts. Behaviour changed since last report

Quick swap of J relay, no change.

Tested terminal 86 , trigger signal on starter relay, goes to 12,3 Volts on key position III.

Tried new ignition switch, no change.

Fire up VIDA

21 start cycles showing clutch switch faults in VIDA, clutch signal out of range.

We ran out of daylight and cold at this point, but I had time to find my spare clutch switches.

Note the1999 starter circuit. The J relay gets12 volts trigger from the key I posIII, BUt the terminal 85 side of the trigger has to be grounded by the 2/76 lock module , after getting the right logic inputs from the ECU

[erikv11]

Oops it is a manual. I never even thought about the clutch switch ...

[abscate]

The fault is almost persistent, but about e/(sqrt( alpha)) the car starts normally. Alpha is the waterfall fine structure constant of approximately 147.

That upset our diagnostic fu.

I confess to parts darting the J relay because it was so easy ( and I was parked next to another car with the same relay)

I am also allowing the possibility of logic failure as the clutch errors in VIDA could be generated by the use of the remote starter switch

[abscate]

Looping back on this no crank problem.

I got my car back from my friend and it’s really interesting

No crank on pos III, just the BOINK of the internal relays.

But.... If you put in neutral and turn to position III and wait 5 seconds , it cranks and starts with the clutch engaged



Forgot to add, we swapped In a brand new ignition switch and no change to problem or symptoms. Before I had a chance to send back to FCP, my favorite lawyer in NJ needed one so I sent it to him

[abscate]

Well, replaced clutch switch with known to be good

Car now cranks with clutch on floor

It also cranks after a 5 second delay with clutch engaged

Waiting for some M56 owners to test this on other cars.......

Update,...it looks like this is special on my car...

Clutch switch tests out close to Specs, searchable here under part number 9472979

[Clemens]

Just an idea: get rid of the clutch switch. This should be possible. The EU spec cars have no clutch switch, so simply bridging the wires shouls work, I guess.
Still weird that it does that 5 second thing.
But then maybe, it only powers that wire for 5 seconds and you never noticed it because you are yoused to pressing the clutch when cranking anyhow.

[abscate]

I thought that too, Clemens. I checked with a few other M56 owners and they report no cranking.

The change in resistance from clutch out ( foot off) to clutch in ( foot down) is 3000 ohms to 300 ohms

The ECU must look for a certain current. On the 1999 the clutch switch has two direct connections to the ECM

I know from previous experimentation that is unlatched logic, if you sit with the key in position iii , you can toggle cranking by depressing and releasing the clutch. I don’t think I held it long enough to test the 5 second cranking, though,previously.

[abscate]

Finally replaced that clutch switch

It measured 477 Ohms closed, and about 1 cm from end of travel it reached 3800 Ohms, then went open circuit

This caused a clutch switch permanent fuault and apparently also allows the ECU to crank the engine after 5bseconds of POS III

This also disable cruise control on ME7 as the same switch is used for clutch dropout,

In short, a new switch cleaned everything up

[scot850]

You should be really proud of getting to the end of this one! Totally impressed.

Neil.