I have a 1990 Dodge B350 RAM 15 passenger wagon/van with 58,000 original miles. Runs great, when it’s running.
Problem: Turns over but won’t start.
Background: I bought it from a guy who worked for Northside Hospital. He said it was a shuttle van that only made short trips. It had problems starting so had been sitting for a while and he bought it cheap when they wanted it off the books. He replaced the computer(rebuilt from AutoZone) and it started right up.
I drove it 5000mi. the next week from Atlanta to Maine and back.
It ran great except for an intermittent starting problem.
It died on me ½ block from my house on the return.
The coil was superHOT! I replaced it and it started right up.
The intermittent starting became more frequent.
I replaced the ignition switch. That seemed to help for a while.
I replaced the computer with a junkyard computer and that fixed it for about 2000 miles.
When it died again, I determined that there was no voltage going to the coil when I turn the ignition switch.
I replaced the ignition switch again. No fix. I replaced the alternator. No fix.
I replaced the computer again (rebuilt AutoZone brand). No fix.
So I hardwired a toggle switch to deliver +12v directly from the battery to the coil +terminal and a volt meter to monitor volts at the coil. It starts right up every time.
Once it starts, after running a few minutes, I can turn the +12v toggle switch off and it keeps running until I turn off the ignition switch.
But if I turn off the +12v toggle right after it starts, say 15-30 seconds after it starts, the van shuts off. This timing is unpredictable.
I’m baffled. I’ve inspected the wiring harness and found no issue there.
I suspect that this has always been a problem with this van and that’s why the low miles. The shuttle drivers probably avoided it.
My questions:
What could be the real problem? Why does it burn up computers? How should I address it?
Am I doing any damage anywhere by applying the +12 volts directly to the coil? Is that my easiest fix? Is it best to keep the +12v switch on, or turn it off if the van will run without it? I want to keep the van and don’t mind a work around fix, but if I could make it right, all the better.
Thanks for your advice and suggestions,
rexBaxter, Atlanta, GA
Along with Rod’s very plausible solution, you may find that the horn relay and this ASD relay are identical parts (I know they are in one particular vintage Ram truck) so you could swap them out to see if your problem goes away and the horn stops working, if those relays happen to be the same in your van.
Are you sure you’re blowing the computer up or maybe you just have some sort of intermittent problem with that ASD that happens to ‘fix itself’ when you fiddle around with the car?
Btw, putting 12V onto the primary of the coil when the car isn’t running could burn that coil up, depending on whether the cam sensor (ie what used to be the function of the points) happens to be detecting that it needs to fire. Just be careful with it, should you not be able to find the exact fix for this problem - that’s what I suspect but could be wrong.
The problem might be with a faulty ignition control module.
Ignition modules function in two modes. These are the start mode and the run mode. When starting the engine, the ignition module goes into the start mode which allows full battery voltage to the coil. This is done because when a cold engine is started the fuel mixture is rich. So a hot spark is required to ensure this rich mixture ignites. Once the engine starts the ignition module switches to the run mode. The ignition module then steps the voltage down to the coil. This done because when the charging system comes on line the voltage that it puts out would burn up all the secondary ignition components such as the coil and spark plug wires.
Remember when older Chrysler ignition systems had a ballast resistor to the ignition coil? That ballast resistor performed the same task. Reduced voltage to the coil once the engine started. But now the ignition module performs this task. So it could be that the start mode of the ignition module has failed, but the run mode still functions.
Thanks guys…, so maybe ignition module, maybe ASD relay. I will check these. For clarification, If I put the 12v straight to the coil and drive it, is that ok? The only risk is if I have 12v to coil with car not running? Is the coil the only part at risk? Should I put a ballast resistor on it if I keep using the 12v? I’ve noticed that some coils say “for electronic ignition” on them and others don’t. How does this play to my situation?
You would wise to purchase a factory service manual for the van. With it you can pin down the location of the faulty wire connection location for the power to the ignition system. Ebay is a good source to find manuals.
See if you have a capacitor attached to the outside of the distributor. Sometimes they short out and have to be replaced. I used to just cut the damned things off to get Ford and Chrysler products to run. Fords used to run and then quit on the road. The Fords would sometimes have a connector that I could disconnect.
When I studied ignition systems, we learned the reason for the dual voltage was because cars wouldn’t start without it.
When cranking the starter, available battery voltage often drops - sometimes down to the 10 volt range. If the ignition system were designed to operate on full 13.2 battery voltage, then there wouldn’t be enough available during cranking.
The solution is to design ignition systems to operate at a voltage that is guaranteed to be available during cranking (~ 9 volts). With the old style “ballast resistor” that Chrysler used, or resistor wires that other manufacturers used, those resistors had to be bypassed during cranking. If they were left in the circuit during cranking, then available voltage could drop to 6-7 volts. Today’s electronic ignition components perform similar function.