Hope u guys can help me

RUNNERKEV

MEMBER
2010 JEEP PATRIOT
102,400 MILES

Hi Hope u guys can help me. I own a jeep patriot 2.0 FWD Auto CVT. My alternator recently gave out, and it was very sudden, no noises or squeeks to give it away. So I got a new alternator, was able to have it installed, but my battery light stays on and it wont charge. No other dash lights come on. My mechanic told me that he doesnt possess the star-scan to see if there are any codes, and that I would have to go to the dealership. Everything works well, lights, radio, all gauges, engine, transmission and so on. I only drove my jeep a few blocks from my mechanic's garage to my house and turned it off, and its been off since. Please HELP! I dread going to the dealership, im a college student with limited money. Are there other possibilities to why its not charging since everything works on my jeep? A fusible link I could replace? A fuse I could buy? Please help me with more realistic solutions before I burn money at the dealership.

2 Replies

CARADIODOC

MECHANIC
33,752 POSTS

Dealership is often the lowest-cost choice. You didn't say what the symptom was with the old alternator but if it was the same as with the new one, you're already out the cost of the misdiagnosis. Start by measuring the voltages on the two smaller wires on the back of the alternator while the engine is running.

I don't know what to tell you to expect for one of the voltages. All Chrysler charging systems used to be so extremely easy to diagnose from the early '70s up to around 1999 or 2000. I was just looking at a 2006 service manual and they show a major change in the wiring diagram that I had heard about, but they're still describing the circuit operation the same as the older vehicles used. One of the smaller terminals should have something between 0 and 12 volts with the engine running. 4 - 9 volts is typical. The other wire used to have full battery voltage, but now it is shown as being grounded. You will find either 0 or 12 volts. Holler back with those readings.

If the Engine Computer is unable to monitor the needs of the electrical system, it will default to running the alternator at 25 percent of its maximum output. That could explain why the warning light is on but there are no apparent problems. The battery could be over-charging slightly or be running down very slowly.