1989 Ford F150 P/U, 4.9 liter(300ci) straight 6 cyl, 4 speed manual, 2WD

1) While driving one day I smelled something burning (maybe electrical, possibly clutch, I continued home and upon checking could find no tell tale signs.

2) Truck sat for about a week when I tried to start it and nothing happened, not even a click from the solenoid.

3) Trickle charged battery out of vehicle for about 24 hours, replaced battery got some clicks but no turnover.

4) Replaced battery and it started fine, immediately took to dealer for old recall regarding starter switch that could result in fire.

5) Brought it home and parked it for about 5 days. Tried to start (see #2 above).

6) (See #3 above), but this time started fine (new battery).

7) Decided to use the old backyard mechanic trick to check alternator by removing negative battery terminal while running, truck died.

8) Replaced alternator(built-in voltage regulator), decided to check via #7 above, this time it continued running, I noticed the dashboard ammeter indicated the battery was charging and no idiot light was illuminated.

9) After 2 days decided to clean out throttle body (FI) with some carb cleaner as per their directions. Upon starting I noticed an illuminated battery idiot light on dashboard, noted dash ammeter indicated battery not charging.

10) (See #7 above).

11) Started looking around the web and found information pointing to fusible links and/or 500 ohm resistor.

12) Located fusible links on wire connected to alternator from starting solenoid. After removing electricians tape, It seemed to be intact, no signs of overheating, feels solidly connected.

13) Found second fuse holder like plastic housing that is opened by squeezing sides and pulling apart between alternator and wiring harness that heads over to the driver side of the vehicle. The wire connected is green with a red stripe. This is connected to the ammeter and ignition switch according to my Haynes manual. The item inside this holder looks questionable as to its status. If a fuse it appears busted. I can’t seem to remove it from its holder either.
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A charging system is usually simple, but this one has me stumped. Any help would be greatly appreciated.

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Thank You,

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JBC

 

I would'nt unhook the battery while the truck is running. Not only can it damage the alternator, when a battery is charging, it creates an explosive gas that a small spark could ignite when the cable is disconnected. (seen it happen. not pretty) I check to see if the alternator is charging with a voltmeter, at idle with lights/acessories on. My chiltons manual shows the same thing with the green wire w/ red stripe going from the voltage regulator to the the dash light, but not showing any in line fuse.

 

Thanks Jade for your reply.

I'm well aware that pulling the negative battery cable has risks both in terms of explosive hazards (which is why I do it outside with plenty of wide open space (a breeze is even better)) and with respect to surges at the voltage regulator, which is why I mentioned it was a "Backyard Mechanic" procedure.

<o></o>The reason I chose to do it is because your battery is not "Constantly" being charged. The voltage regulator is constantly monitoring the battery, (which actually runs your vehicle) and when it senses the battery voltage drop below a predetermined value it sends a charging voltage to the battery to bring it up to a predetermined level. All the rest of the time (since the alternator is constantly putting out power) the regulator is sending the voltage to ground usually through a power resistor. So I chose to take a risk instead of having to wait for my "new" battery to "request" a charge. Not to mention the fact that doing it the risk way eliminates possible false indications as outlined above. I know that it's not the best way and I don't recommend it either.

Again thanks, but what I'm really looking for is help with my problem not my troubleshooting practices.

Later,


JBC

 

The red with green stripe wire is the one that "turns on" your alternator. Check it with a meter. Should show 0 volts until igniton switch is turned on. Then should have 12 volts. If no volts with switch on, back track with the meter to find the problem.

 

Thanks fmr9,

I wasn't sure what the voltage was supposed to be. Schematics are $18.00 delivered, and I hadn't decided to shell out the money yet.

1) As stated above there is some sort of fuse inline between the Ammeter/Starter Switch and the Alternator (green/red wire). I used this point to probe and received the following indications.

MM = Multimeter

Note: 1) When I jumped the fuse holder the engine RPM was reduced along with the voltage drop. 2) The idiot light is on while jumped and off while disconnected.
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It seems to me that the Alternator/Voltage Regulator is bad, except for the continuity indication, unless it’s done on purpose via the switch to ensure no voltage is seen at the alternator when the engine is off.

<o></o>There are pros and cons to this Alternator/Voltage Regulator combination (as seen by the owner).

<o></o>1) With one replacement you replace both components (eases troubleshooting).
2) If one component dies you have to replace both components (undue replacement).
3) Two components combined increases the per item cost (more costly repair).
4) The power handling ability is reduced due to smaller semiconductors (more easily damaged).

<o></o>Looks like the automotive industry has once again stacked the deck in their favor, of course I’m not surprised!

<o></o>This Alternator/Voltage Regulator has a lifetime warrantee. The reason I’m looking for help is because before I return it for a new one, I want to make sure that there won’t be a repeat performance (something causal in the vehicle).

If not it would appear that either I did it when I removed the battery cable (which doesn’t make sense because it ran afterwards and I didn’t reconnect it until the starter switch was turned off), or it was only marginally good to begin with, or both.

<o></o>Rest assured I won’t make that mistake again, with these inferior counterparts to the old more sturdy two component system.

<o></o>Thanks for any help anyone has to offer,


JBC

 

Not sure if I can be of much help. Looked in my service manual, but it is for '91, and it does not show any fuse, fused link, or anything else in the circuit on the green with red stripe wire.
I recently did the 3g alternator upgrade, for less then $50 using a salvage yard alternator. The testing I did was just checking to see if the green redstripe wire delivered 0 volts with switch off, and 12 with switch on. Then I checked across the battery terminals. With everything off, got about 12.5 volts. With engine running, went to 14.6. When I turned on everything I could, like headlights, wipers, blower, radio, etc. Voltage dropped to 14.4 and stayed there. I would assume if yours is working properly you would see similar numbers.
I think you have the 2g alternator. It is known to have problems due to bad connection thru the plastic plug. This has caused numerous fires. To avoid a potential fire and because I plan to go to an electric fan, I went with the 3g.
You should check your plug for damage due to excessive heat. If it is not in good shape replace it or consider the 3g upgrade.
The alternator you purchased can be tested to see if it is working properly. There have been numerous discussions about the "lifetime" warranty and really cheap low quality rebuilds. Some guys have gone thru two or three rebuilt alternators from Auto Zone or Pepboys before they gave up and purchased a good rebuild.
You could try posting in the electrical forum. Some really sharp guys there.
Good luck Frank