1990 Aerostar 4.0L 165,000 miles.

I have been fighting the weirdest problem for month's. Many people here have offered excellent suggestions but to no lasting avail. The major overall symptom is the random complete loss of power or dramatic loss of power. Some mornings you come out to the Van and there is no power anywhere but the battery. Shake and pull wire, close door, slam hood. Any or all of these and the Van power may come back temporarily or may come back and be fine for a few days. Also, out of nowhere if you put a load on the electrical system such as lights, or air, the power will drop all the way to off and then kick back on.

List of things replaced: Positive and negative battery cables, starter, starter solinoid, starter relay, altenator, voltage regulator, battery, fuel relay, eec relay, fan clutch, radiator, water pump, heater core, complete air conditioning system.

All flow components cleaned maf, ic, etc. All connections checked, pulled on cleaned, etc.

I am out of ideas. The car has actually stalled a couple of times while stopped at lights. Very troubling. The fact that all electricity goes away is the sticking point. There are not that many points that can stop all electricity.

Any other ideas would be greatly appreciatted.

Thanks,

John

 

Bad body ground. Just because the connection looks good does not mean it is...

Next time it happens check with a voltmeter from the positive post to all different ground points. If you don't find it there then start checking from the negative post to see where the power stops...

 

this is gonna sound kinda dumb but did you replace the battery itself.it might no be all of your problems but the battery may be bad.

 

Yes, sorry, the battery was also replaced. It is in the list of replaced items. Also, have had battery and altenator load tested.

Thanks,

John

 

Anyone know the location of the main Grounds. I know here the engine ground connected to the battery is, but where are the main body/firewall/chassis grounds?

Any help would be appreciatted.

Thanks,

John

 

I know you said earlier that you checked the connections, but have you tried reseating the connectors? In other words, physically disconnecting them and then reconnecting them, especially the main EEC wire harness connector at the firewall.

 

I think I finally found my power problem. After replacing about everything at least once, I decided to replace the Alternator myself. The previous 2 had been through a garage. After pulling out the alternator, there is a round connector from the wiring harness that goes to alternator with one plug for the alternator and another for the voltage regulator.

I pulled the cable off since the new alternator requires, a new crimp on alternator plug be used. They claim the original is a one use plug and repeated on off usage causes problems. This cable was covered with electrical tape and a plastic sleeve covering. When I got the covering off so I could cut off the old connector and crimp/solder on the new, low and behold the 2 wires going to the voltage regulator were crushed together. My guess is one of the times in the past the cable got crimped under the alternator as it was being installed. I repaired the wires, crimped the new plug and put on the new alternator and the difference is night in day.

It is too soon to tell if this is a complete cure but the symptoms have disappeared so far. The way the wires were crushed they could short sometimes, open sometimes, work partially or work normally.

I hope this helps others who have had similar problems.

Thanks for all the help.

John

 

The problem with the power drop is gone and I think the repair to the alternator cable solved that one, but one of the symptoms from before are still there.

When I start up once every 5 to 10 times, the first thing in the morning, as I go down the road the volts on my volt will start to climb. At idle, instead of the normally constant 14 to 14.5 volts it will shake constantly just a little. When this happens the transmission will jolt when changing gears, turning on anything electrical will cause the voltage to go crazy for about 5 seconds and then mostly stabilize. The longer I drive, the worse it gets.

This happens with no electrical items on but the engine. The cure is to pull over, stop the car and restart it. Everything will be perfectly normal after that for the rest of the day and maybe several days after that.

Since I have changed virtually everything to do with the electrical system already (see previous posts), I am convinced the computer is going crazy and turning the car off and back on is the equivelant of rebooting it. With the variety of devices this effects, I can think of nothing else that could cause it.

Am I correct in assuming the Computer controls the Voltage Regulator in the alternator or is there some other device also.

I know all of the other symptoms get their control from the computer. There are no codes when this happens. I have reset the computer more time than I can count by disconnecting the battery.

Any thoughts other than grounds, alternators, batteries, relays or these items are appreciatted. I have changed each of these, somtimes several times, and no change.

Thanks,

John

 

Here's something else. There are diodes in some of the wiring harnesses. If these go bad, they can cause weird problems. A wiring diagram will help locate these, but I recall some labels on the wiring that say "diode" on them.

 

I think I have found the problem to the weird occasional power problem and a previous problem that re-occured where all power in the car would go away and suddenly come back when you closed the hood or shook the wires.

The problem re-occured a few nights ago. After going for several days without major problems, my wife drove home from work and when she turned off the engine, once again all power was gone in the car. I came out and shook everything carefully and finally found the wire that was causing the problem.

There is a red wire between the starter solenoid on the starter and the starter relay on the top driver side of the engine fender wall. It is a 10 guage wire and gets bolted on by itself on one of the terminals on the relay. When I carefully would shake this, it would cause all power to go out and then all power to go back on. What did not make since was, when I took the wire off completely, the power would be on, but of course the starter would not start.

I determined the top 8 to 10 inches held the problem, so I cut off that portion, including the terminal crimp, and then stripped all the insulation off to see what the wire looked like. The top 6 inches were very black, as if it was arcing, but the wire was not broken in any way.

I crimped a new piece of wire and new terminal eye onto the existing wire and reconnected it and the power seems very stable now with no strange symptoms.

I can only guess that somehow moisture got into the wire and slowly caused it to deteriorate. Under certain conditions the wire would arc inside and trip some kind of circuit breaker in the electrical circuit. I really have no idea why this wire that was not shorting out against anything elese could cause all power in the car to stop, but hopefully, it's repair has caused the problem to go away. I will totally replace the wire soon.

Sorry for the long message but this has gone on so long I felt a full explanation was warrented.

John