rhubarb74roadster

Short version (updated) :

-Had voltage swings on and off for months .. anywhere from 10.8 - 15 volts

-Started getting high voltage warnings (15+ .. would last a minute or two)

-One day car stopped getting voltage from alternator

-New alternator and battery .. just put in a new ECM. Still not getting any power from the alternator.

-Good power from the alternator terminal to the battery. Grounds look good.




Having a power issue with my 2001 (56K miles).

For months, my voltage would swing back and forth between 10 and 15 volts. Some days (or a few days at a time), it stays at 13.8v, other days it would float high .. sometimes low.

At one point I replaced the battery. no changes. Checked all the grounds and the ground blocks, they are fine (car has been in the south all its life .. and only driven during nice weather .. no corrosion at all.

So then, for a few weeks, the voltage would go really high .. over 15volts for a minute or two. DIC would report an overcharge situation .. but as I continue to drive, it would usually drop back down .. sometimes to 13.8 .sometimes lower.

Then one day I drive to work .. voltage is low (around 11v) and steady. No swings. When I go to lunch, I notice its hard to start. Voltage is now 10.8v. Drive about 5 miles .. A/C stops working. Leave from lunch .. car is really slow to turn over. At this point I figure out that I am running on just the battery .. no power at all from the alternator. The car dies just before I pull into the parking lot.

I pulled the battery and charged it that night. Dropped it back in the car the next morning and it fired right up. Drove the car home on battery alone.

I replaced the alternator and still am not getting any power to the car from the alternator. The voltage from the battery to big terminal on the alternator is 13.8 (without the car running).

Installed the new ECM tonight. After the 'relearn' procedure, the car fired right up .. but voltage sat at 11.9 and would drop as I turned on the headlights or stepped on the brakes. Looks like I am still not getting any power from the alternator.

Where should I look next?

Assuming I do not have two bad alternators, where else should I look? Is there any way I can test this?

Big Duk

The only thing you can do without a load tester is check the harness connections & grnds. It is possible that it is caused by a faulty instrument cluster or pcm too! Doubt you have 2 bad alternators. Good luck! It may be stealership visit time.

OkieBikerDude

If you are measuring 13.8 v at the battery with the engine off. What do you measure across the battery terminals with the engine running?

On my wife's '89 I replaced the alternator twice with "remanufactured" units. I got about two years on the first one and the second one was bad over the counter. I think it happens more with rebuilt units, but it does happen.

OBD

rhubarb74roadster

I will go out tonight and check the voltages with the car running .. both with the big wire connected to the alternator and without.

Is there anything that I can test for with the DMM on the three wire connector coming from the ECM or the pins off the alternator?

rhubarb74roadster

Ordered an ECM. We will see if that fixes the issue. If not, I will have a spare that I can send for a tune

rhubarb74roadster

Updated with new ECM .. still no love.

See first post.

Artic

my 2004 manual shows two wires from the pcm, one red and the other gray to the generator and two red wire each protected by a fusible link to the starter. if you have a meter check for continuity and the condition of this wires. do you have any trouble codes? hope this helps.

theheartbeat

beat the s### out of it with a hammer

dgrant3830

The battery, alternator and starter, all come together at the starter solenoid. Between the alternator and the solenoid is a fuseable link. I suggest looking at the solenoid. Remember that its electrically hot all the time unless you pull the negative on the battery.