1991 Ford Ranger Electronic troubles?

LODLO

MEMBER
1991 FORD RANGER
4.0L
V6
4WD
MANUAL
148,000 MILES

The amp meter sometimes goes from low to high and back again, The air conditioning no longer works, so I have replaced all related parts and it still does not work. But now the dash lights started blinking intermittantly and/ or the wrong lights will come on for something else. They flash crazily.
The heater only works with the fan on high.
The engine stalls sometimes when in idle and then the gages go nuts and it spits and sputters and also may make a clicking noise.
It seems that more and more electronic items are malfunctioning and related parts are having to be replaced.
I want the air conditioning to work but can't find the problem, just get more problems.

1 Reply

CARADIODOC

MECHANIC
33,916 POSTS

You haven't included any details or test result to analyze for the air conditioning system, but the electrical problems sound like a generator problem. You can do the first part of the test yourself with a digital voltmeter. Measure the battery voltage with the engine not running. If it's around 11 volts, it has a shorted cell and must be replaced. If it's good but discharged, it will be close to 12.2 volts. Charge it at a slow rate for an hour. If it's good and fully-charged, it will read 12.6 volts.

Next, measure that voltage again with the engine running. It must be between 13.75 and 14.75 volts. If it is low or high, suspect the voltage regulator or generator. This voltage has to be measured when the problems are occurring. If the voltage is okay, the next part of the test requires a professional load tester to test for maximum full-load current and "ripple" voltage. If the generator has one failed diode of the six, you will only be able to get exactly one third of its rated current, which isn't enough to meet the demands of the entire electrical system under all conditions. That bad diode will also result in very high ripple voltage which can confuse computers and interfere with computer sensor signals. That is where the erratic operation can come from.