Hello all!

I have a 1990 Dak, 6cyl 4.9 Automatic. I've owned her for a few weeks now.

A week ago, the radio died on me in the middle of driving, and i noticed the battery level was pretty low (about 10 volts). About 10 minutes later, it jumped right back up to 13.5. The next day, same thing, except it didn't start charging again until I'd parked the truck and fired her back up later. So, naturally I assumed it's probably the alternator on the fritz.

Upon inspection, the previous owner replaced the alternator with on marked (in yellow paint) as being from a '91 Ram. They had cut and spliced the wiring harness, and wrapped it in electrical tape. I rewired the splices, double-checking all the connections. The battery is fairly new, connections and cables are good. After this, the truck seemed fine.

Until last night; same thing on the way back from a fishing trip. Only this time we were returning in the dark, so the lights where draining the battery much faster than any other time this has happened. We made it about 5 miles before the lights dimmed, the dash went funky, and the truck started stumbling and misfiring badly. Luckily it didn't die out completely until we got to a safe place to pull over. We got a tow home.

I'm assuming at this point that I do just need to replace the alternator. Is there anything else I should be looking at? I don't want to replace an alternator, and find out that something else small could be causing a short.

On a side note, I've been playing with the non-working A/C system. In an attempt to diagnose things, I bi-passed the the high limit sensor. This got the compressor to run, so I left it bi-passed for now. Could this be in any way related?

Thanks for your help guys!

 

Ya it sounds like it might be the alternator or more bad wires/ connectors. Most auto parts stores can test the alternator for free.

 

The Voltage Regulator could be shot. Like Crazy4x4RT said Have your local auto parts store spin check it for you and you'll have a better picture of whats F***ed

 

If the problem lies in the regulator the whole computer will have to be replaced, just as a warning.

 

also check the terminals on the battery. i had a daytona that did that and all it turned out to be was a loose terminal.

 

Thanks guys, I'll have the alternator checked. Any good way to test the Voltage reg and/or computer in the mean time?

 

No easy way!

 

Here's the Diagnostic section on the Alt and Computer
http://www.4shared.com/document/DlbwLO4e/Charging.html

 

one of chrysler's dumber moves....I will be rewiring my 89 to take an external regulator, since the computer will be thrown out....

 

Ok guys, had the alternator spin-checked. Oddly, it checks out good... I reinstalled it, this time soldering, and really sealing the spliced harness. Took it out for a drive, and it's tough to tell, but I'm not convinced it's charging. Guess I'll know in a few days!

Also, I took the time to check the codes on the check engine light, as described in the faq. I'm getting a 12 and a 41.

"12 - Direct battery input to PCM was disconnected within the last 50 key-on cycles (normal)" Not worried about that, off course that's going to come up.

"41 - Generator field not switching properly" Now help me out here. That doesn't sound good, and sounds related. Any tips?