Auto electrical problem

Tiny
MARKYMARK
  • MEMBER
  • 2001 DODGE CARAVAN
  • 6 CYL
  • FWD
  • AUTOMATIC
  • 150,000 MILES
'01 Dodge GC Sport 3.3 engine. Battery icon light came on; then systems began shutting off one-by-one. Radio, heater fan; then warning lights and bells began to flash intermittently; wipers began operating (sluggishly) by themselves; yet the vehicle kept running.
Battery tested ok.
Bad Alternator?

Weather: snowy/ wet driving conditions.
Do you
have the same problem?
Yes
No
Saturday, December 4th, 2010 AT 7:33 PM

3 Replies

Tiny
CARADIODOC
  • EXPERT
Recharge the battery on a slow rate for an hour or two, then use an inexpensive digital voltmeter to measure its voltage. If it's near 12.6 volts, it is ok. Measure again with the engine running. It must be between 13.75 and 14.75 volts. If it is low, dig down to the back of the alternator and measure the two voltages on the two small wires that are plugged in or bolted to the back. The engine must be running for these tests.

One terminal will have full battery voltage. The second one should be less, but if you find 0 volts, the brushes are worn. They can often be replaced without removing the alternator from the engine.

Caradiodoc
Was this
answer
helpful?
Yes
No
Saturday, December 4th, 2010 AT 7:41 PM
Tiny
MARKYMARK
  • MEMBER
I had the alternator tested, it was operating normally. Technician suggested testing ECM. Could that be the problem? Is it something I can replace myself?
Was this
answer
helpful?
Yes
No
Sunday, December 5th, 2010 AT 6:01 AM
Tiny
CARADIODOC
  • EXPERT
I'd really want to know what those two voltages are on the back of the alternator before I headed for the least common cause, (and most expensive). If you can get to the connectors on the Engine Computer, (Electronic Control Module - ECM / Powertrain Control Module - PCM), you can take the important reading on the brown wire / gray stripe in pin 8 of connector 1 instead of standing on your head to reach behind the alternator. You will measure full battery voltage, 0 volts, or something between 4 and 11 volts. 4 - 11 volts means that part of the circuit is working properly.

Caradiodoc
Was this
answer
helpful?
Yes
No
Sunday, December 5th, 2010 AT 6:56 AM

Please login or register to post a reply.

Recommended Guides