Any VW Mechanics here?

[Travelover]

I'm hoping someone has some insight into diagnosing a no spark condition on a VW. Vehicle is a 1995 Vanagon (Eurovan) with the 5 cylinder engine that my friend owns. The vehicle was running when parked, but has sat for about 5 months.

My mechanic days ended with points and condensers, so please bear with me. The ignition system on this van has a distributor with a hall effect sender which feeds pulses to an engine control module which feeds power to an ignition module which feeds an ignition coil which feeds high voltage to the center cap of the distributor.

The coil is getting 12 volts. The hall sensor is sending a pulse to the engine control module. The engine control module is not sending a pulse to the coil while cranking BUT when you release the key from the crank to the run position, the coil sparks a couple of times until the engine comes to rest. I think this last part is an important clue - somehow it has spark the instant you quit feeding power to the starter motor. I checked the engine control module relay and it is getting power in both the crank and the run ignition switch positions.

The engine control module is $300+, so we'd like to narrow down the possibilities before replacing that. All grounds have been cleaned and verified. Battery is new and fully charged. Any other suggestions?

Thanks in advance.

 

[Soundguy]

if I was froggy.. I might use a manual starter bypass switch and clamp it around the solenoid and get up int he driver seat.. be safe.. etc.. and get her to run position, and see if that makes her start.

then see if any codes set

not a mechanic!.. and yes.. I'm a points and condensor kind of guy.. I know modern electronics.. but not specialty automotive stuff gobelty gook..

 

[tcartwri]

Might be the ignition switch. Electronics typically don't go bad from lack of use, but switches do.....

 

[tcartwri]

From a little googling it seems bad switches are a common problem on this era of vw's. It makes sense considering your symptoms.

 

[Travelover]

Thanks, guys - good suggestions.

 

[BeeferMan]

I'd also check for good grounds and battery cable connections, could be that with a questionable ground/connection the draw from the starter is dropping the voltage to the control module to the point where it doesn't generate a proper spark, when the starter no longer draws current the voltage rises sufficiently.

Corrosion/bad ground also matches with the sat for five months info...

 

[Soundguy]

could be corrosion in a plug.. etc..

 

[logdog]

I own and have owed several old watercooled VWs. I found vwvortex.com pretty helpful. They have model and engine specific forums.

 

[Travelover]

I own and have owed several old watercooled VWs. I found vwvortex.com pretty helpful. They have model and engine specific forums.

Thanks, I have a post over there, too. I've found the folks here to be pretty practical, so I figured I'd ask here, as well.

 

[KubotaSam]

I second Bererman's idea. Starter drops voltage to a point that module does not work. When starter stops drawing the voltage rises and module works. Can you put a voltmeter on the input to the module?

 

[Travelover]

I second Bererman's idea. Starter drops voltage to a point that module does not work. When starter stops drawing the voltage rises and module works. Can you put a voltmeter on the input to the module?

Technically I'm sure the answer is yes. It has a fist full of wires that go into it, so I'd need to figure out which one is the power in. I did find the relay that powers it under the dash, so I might be able to check voltage there.

 

[banjodunn]

G'day don't know that vehicle but can you check the back of the ign switch or at the loom plug for the switch and see if you can work out which is the ign feed wire out of the switch ( test light to see which wire powers up when ign turned to on), and then turn it to the start position it should retain power if not then throw ign switch to the s%^&house and replace.
Another way to to check switch is faulty is to feed power into that ign wire and then crank ( you can do this by backprobing the plug with a jumper wire from the batt).
Good Luck

Jon

 

[orezok]

I would check for rodent damage to wires also.

Sometimes it's a barely visible bite through a wire.