My Westy kills ECUs... 3 in 3 weeks

[afmercure]

Vanagon 1990.

1st ECU:
I started having a hard time starting it. Mechanic says it's the ignition swith and replaces it. Problem comes back and gets worse, to the point where the van starts... sometimes. The engine cranks and cranks, but never starts.
Some day, I'm able to start it and take the van to the garage. Mechanic replaces the ECU and everything works fine.

2nd ECU:
A few days later, the engine doesn't start. Well, it starts but dies after 2 seconds instead of keeping idle. At that point the fuel pump gets 0v. Samba reading, tracing back to the fuel pump relay: no voltage on pin 87 at startup.
Replace both relays - nothing. After a few trials, back to the original problem: engine cranks, cranks, but never starts
Towing time.

3rd ECU:
Mechanic replaces the ECU and the van is back to life... for 3 days. Today, it cranks and cranks, but never starts. This time the pump primes when I turn the key.

My mechanic says all grounds are good. He now suspects the alternator (3 year old refurbished Bosh) might give too much current (or voltage, I guess?).

Any idea before I get it towed for the 3rd time in a month?
Thanks!

[MidwestDrifter]

Check your alternator output voltage. Maybe installing a voltage gauge temporarily? I am not sure what level of high voltage could kill an ECU but you would certainly notice it on a gauge.

Check your plug wires. If they are leaking/sparking anywhere near the ECUs wiring, this is bad mojo.

Thoroughly inspect the harness for cracked or damaged wires. It may be necessary to pull back the outer sheath on the bundle.

Check your ground paths, including the harness ground pins. If the ECU doesn't get continuous ground, I have heard that it can cause the ECU to ground internally, damaging it. (if someone with more experience could confirm this)

You are using the correct OEM relay? The relays MUST have the correct voltage spike suppression circuitry inside, or they can damage the ECU.

Have you replaced the ignition coil and ignition module? I believe it might be possible (though exceedingly rare) for a ignition module or coil to cause high voltage levels to leak back into the ECU. This could result in damage to the circuit that switches the ignition module.
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[Vanagon Nut]

[Ahwahnee]

Those are good suggestions but... I wouldn't totally rule out the possibility that you have an intermittment problem that recurs & clears in such a way to lead you to believe you have had a series of ECU failures.

FWIW -- what I use for a quick on-the-road peek at voltage...

http://www.amazon.com/Equus-3721-Battery-Charging-...tage+meter

[afmercure]

Thanks for all the suggestions. I'll have to investigate a few things. But for the questions I can already answer:

- Yes, using OEM relays.
- No, haven't replaced coil or ignition module.
- The van is a Multivan (Weekender with pop-top). That ground wire looked good, but I'll go trough all wires again.

I like the Equus voltmeter/monitor idea. But for now, the van doesn't start at all, so it wouldn't help much.

Thanks!

[BillM]

I would check the hall sendor and its
wiring. It is in the distributer. You will
see a plug and some wires on the side
to your left at the base of the distribute
body. Push and pull gently while someone
tried to start. Also listen if with the key
in run position if you can hear the fuel
pump kick on/off while your moving those
wires. This of course only checks the
wiring but that is usually what fails.

[Vanagon Nut]

[pioneer1]

I would reinstall one of the old ECU's to see if the van starts-there could be a bad/dirty connection in the amphenol (connector) of the wiring harness.
_________________
"Always waiting for tomorrow ruined everything"

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'76 Westfalia project

[mwsnow]

[BillM]

The proper way to diagnose would be to follow the Fuel
injection repair manual specific to your van. Using a
multi meter,test light and fuel pressure gauge follow
it from the beginning not skipping any steps. Write down
all your results comparing them to the specs in the guide.
If you replace any parts along the way keep the old ones
till your 100% you nailed the problem. I find it hard to
believe it killed three ECUs though I guess it's possible.
I have personally never had an ECU go bad. I have seen
one that was proven dead from another Westy owner
and it had visible damage on the circuit board. You could
see the componets inside that were cooked. Plus it had
that fresh baked electronic smell....
This is a good time for digitool man...might be worth renting
one from Vancafe. I would loan you mine but it hasnt
been returned to me from the last person I sent it out too!
You may also want to build a "test" harness that Mark came
up with. Little bit of wire,couple connectors,and a fuse holder.
I think every stock powered Vanagon should have one in its
parts bin. Last year it helped one of the people at West River
be able to drive their Westy home instead of a 300 mile tow.
_________________
Bill M
87 Westy

[Jake de Villiers]

[afmercure]

Wow, lots of suggestions - will have to try them... Here's what I had time to (or felt comfortable to) try so far:

- pioneer1's suggestion to retry one of the old ECUs gave me an idea. I don't have them, but I unplugged the current ECU this morning, thinking it might reset it in some way. When I came back tonight, I reconnected it, but it didn't help.
Note that ECUs #2 and #3 are used, so just as old as #1.

- Hall sender - Bentley 28.43
Voltage supply: ok
Function checking: mentions using US1115 volt tester. Can I use my regular multimeter in VDC mode?
Also tried wiggling with wires while [attempting] starting, but it didn't help.

- ECU connector tests - Bentley 24.61
step1 (voltage supply): ok
step 2 (wire to ignition coil terminal 1): ok
step 4 (fuel pump): I hear it when switching ignition
Not done yet, but planning to (involved removing connectors in the engine bay and it was getting dark):
steps 3 and 5 (injectors)
step 10 (Hall sender)

- Also planning to do 24.56 (injector voltage supply checking). Again involves a US1115 tester, so wasn't sure I could just use my voltmeter??



But I don't have much time these days, so I might just get it towed (again ) to a shop.
But if the ECU is fried and they need to replace it (again ) in order to get the engine running, how will they make sure they find the root cause so that the problem does not come back?
Should checking the alternator be enough?
This plus following all steps in the fuel injection repair guide as suggested by BillM?

*edit*
I also checked and paper sanded ground connections in the engine bay, and they look good (connectivity test). The ECU ground also looks good, but I haven't tested it (other than step 1, Bentley 24.61)

[afmercure]

[Vanagon Nut]

[festa-Doka]

Hei guys first post here ... I have the same problem changed out the ECU Digijet version 2.1 DJ did the rotor test had spark and clicking plus fuel ... so I checked at the ECU conector ... holy crap !!! was there a few things which did not give the right readings (AFC system check 24.21)
first test ... no power ... second ok .. and so forth ...
should I change the wires and see? just getting down with this problem
I was thinking of rebuilding the wire network and see if that will work? anything will be of help ...

Another thing are the DJ yellow injectors interchangeable with the other ones? and do they have the same resistance?

Chris ... Festa

[von]

The rear wiring harness got melted as the shroud heated up to burn temperature whilst laying on the metal above the muffler. All the wires had to be cut. I see the yellow and brown wires, easy to splice but the 14 white wires seem to not have any way to distinguish one from another.

Before installing another EFI harness I'd like to find out if anyone has ever tried repairing a similar disaster and if they can advise me.

[von]

Can anyone tell me what the 14 white wires in the EFI harness are for?

[jptech]

Hi Friend,

Sounds like youve got your hands full, The Digifant control module or DCM or ECU is one of the most durable and reliable control modules in use today.

I have some questions the answers to which may fix this issue. What was the original problem ? What was measured or observed ?

There is an industry-wide caution to never, never connect or disconnect an ECU with the ignition key switched ON. Has tis rule been followed 100% of the time when diagnosing this problem ?

John

[pushkick]

the one thing to check with a meter is the grounds this ecu switches the injectors to ground and just about everything is done that way to keep the spark suppressed. you have to check with a vom

the voltage for the ecu has to be the correct voltage or their will be strange problems. loose wires from the fuse panel or wires that are grounded ( the plus wires) some where in the system could pull the plus voltage down intermittantly this would cause problems in the ecu.
sometimes a skinned wire will weld itself to spot and get hot enough to burn free.
_________________
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1990 vw automatic camper

[insyncro]

Pin test the harness