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post #1 of 12 (permalink) Old 02-21-10, 05:16 PM Thread Starter
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Question Intermittent charging 1991 E350

I have a 1991 motorhome that has a low voltage problem and a no charge situation. The intermittent charging prevents use. I have replaced the 100 amp alternator, the voltage regulator, the Delay switch to the house battery and the switch which jumps between both batteries.
I have followed the Ford tests 1. Disconnect the regulator and jump between A and F. The alternator now puts out 18 volts and I get about 14 at the start battery. 2. reconnect the regulator and jump from Batt to field on alternator. I now get 18 volts and about 13.5-14 at the start battery.
I have checked the field lead on the alternator and it was loose. A professional electrician tightened the connector and it ran fine for a while, but at freeway speeds it slowly declined in out put again. There is so little wire at the field lead I am afraid to cut it and replace the connector.
Both the Batt wire and field wire are held and lead into a square rubber part attached to the alternator. Can the field wire be cut outside this part and a new wire routed to field?

FYI the low voltage is also intermittent. I have cleaned what grounds I could find/see and cleaned all leads going into the starter relay. Any suggestions here?

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post #2 of 12 (permalink) Old 02-21-10, 06:53 PM
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Re: Intermittent charging 1991 E350

It sounds like it must be that same connector. If that's the 3 wire connector, you can get it at Rockauto, one of our sponsors. Look for a Electrical-Connector : Voltage Regulator Connector and see if that's the connector. You can cut the three wires and splice it in. Check the sponsors forum and get a code to get a discount available for our members.

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post #3 of 12 (permalink) Old 02-22-10, 07:57 AM Thread Starter
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Re: Intermittent charging 1991 E350

Thanks Bert. It is the 3 wire connector type. I will order the connector as you suggest, and get the discount, and solder and shrink wrap the connections to make positive connections.

The field wire on the alternator which was loose may need replacing. (it leads to one of the 3 wires on the connector) Can it be bypassed? I ask because it is very short at the alternator and first goes into a rubber block and then to the connector. The vehicle was in a wreck at one time and the field wire may have broken strands/one or two left so that at freeway speeds it gets hot and current drops off enough to stop charging until cool. Thanks for the help.
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post #4 of 12 (permalink) Old 02-22-10, 08:33 AM
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Re: Intermittent charging 1991 E350

I'm not sure about bypassing because I'm not sure of what it is. If you could get some pictures that might help. Does it look like a RV installation or Fords?

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post #5 of 12 (permalink) Old 02-22-10, 09:46 AM Thread Starter
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Re: Intermittent charging 1991 E350

It looks like Ford. On the alternator is a small rubber block bolted below the the Batt and Field couplers. The Batt and field lead into the rubber part and then down to a loom where the Batt goes to the starter relay and the field wire branches over to the regulator connector along with S and A wires coming in from another loom.

With the key off, A (blue and white ) reads hot. S (Green and Red) reads cold and F (orange and blue) reads cold.
Key on, A and S read hot. F reads cold (may be loose F connector at alternator) is this normal?
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post #6 of 12 (permalink) Old 02-22-10, 11:22 AM
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Re: Intermittent charging 1991 E350

The field terminal is what triggers the alternator to charge. Try with the engine running. After you replace the connector I'd see what it's doing. That may be all that's wrong. Connections cause a lot of problems.

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post #7 of 12 (permalink) Old 02-22-10, 12:41 PM Thread Starter
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Re: Intermittent charging 1991 E350

Well Bert, now its gotten worse. Yesterday it was intermittent, but now with engine running nothing. A jumper wire from A to F at regulator connector yields nothing. From alternator Batt to field jump yields nothing as well.

In your experience, is anything in the fuse box connected? There has been a fuse blow situation recurring with the running lights/tail lights etc. An examination of the fuse box had fuses in locations where only one side of the fuse had heat the other side went to a blank hole. The ford manual said fuses in situations like this could cause electrical problems so I just pulled them.

Now, while checking wires yesterday I turned on the light switch on to the running lamp position and smelled burning and observed the back of the main switch glowing. Now it blows fuses constantly. Could this have blown the alternator?
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post #8 of 12 (permalink) Old 02-22-10, 12:54 PM
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Re: Intermittent charging 1991 E350

I doubt if it caused the alternator to go out. It sounds like you have soe electrical issues with it though. The alternator could be out but you need other things repaired too. Hard to do without being there. You'll have to replace the headlight switch and possibly the connector and see what fuses really need to be in and the proper amperage. Then when the alternator connectios are repaired, see what happens. Good luck and keep posting as you have.

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post #9 of 12 (permalink) Old 02-22-10, 03:26 PM Thread Starter
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Re: Intermittent charging 1991 E350

I checked the fuse to the running lights and replaced it. Now everything is up and running except it still has low voltage at the voltmeter. The alternator is obviously blown, but guranteed so it gets replaced.

Now my electrician friend came over and I showed him where all the wires had been tapped in to, and I think the main line is cut by one of many splices so that the power now has to backfeed through a radio or something. A real drag.

His question, is where does the power for the field originate, meaning does it go from the fuse panel, up to the key and then across to the loom and regulator? Next the S circuit how does it originate? I ask because I could always run new leads completely by passing the tapped wires. Its a mess. There is a TV tuner behind the dash and a new radio which sounds fine but hot wires are hanging just cut and the TV does not work. I can live without a TV. But not a charging system.

The guy who did the work left his business card it said "Walt Disney enterprises" "M. Mouse electrical technician." Thanks for your interest
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post #10 of 12 (permalink) Old 02-22-10, 07:17 PM
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Re: Intermittent charging 1991 E350

Here's the Ford wiring diagram for the alternator circuit.[IMG][/IMG]

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