92 740 No start....

[Bjorn Sunde]

I drove my 92 740 home yesterday and parked in the driveway. Today no
start.... It appears that there is no spark in the ignition system.
Tested all the components (wires/cap/coil) on another 740 and they all work
great, but not in mine.
What could this be?
Any hints would be helpful.

 

[James Sweet]

I drove my 92 740 home yesterday and parked in the driveway. Today no
start.... It appears that there is no spark in the ignition system.
Tested all the components (wires/cap/coil) on another 740 and they all
work great, but not in mine.
What could this be?
Any hints would be helpful.

The usual problem is the ignition power stage, I think this year has one,
it's mounted to the inner fender near the left-front corner of the car.
Small block that says Bosch on it screwed to an aluminum heatsink.

 

[Bjorn Sunde]

I switched it for one that I know was good (came off a car that runs) and
put mine in the other car. The other car still starts, mine no go..

 

[James Sweet]

I switched it for one that I know was good (came off a car that runs) and
put mine in the other car. The other car still starts, mine no go..

I suppose the next thing to test is the crank angle sensor, there's not much
else to the system and this car is new enough that the engine wiring
shouldn't be crumbly like the pre '88 cars.

 

[Bjorn Sunde]

Where is it located on this car?

I suppose the next thing to test is the crank angle sensor, there's not
much else to the system and this car is new enough that the engine wiring
shouldn't be crumbly like the pre '88 cars.

 

[Bjorn Sunde]

Found it.. Located on the back of the engine, above the flywheel.
I was going to test it, but after wiggeling the wires while tracing it to
the connector the car started. Must be a bad connection where the wires go
into the sensor.
Thanks for your help James.