Alternator Help

[Iggle]

Hey guys,

Here is my problem:

I got an old Jeep and it had the old Delco 3 wire style alternator. I drove it to the store one day to get some cold beers and came out and it wouldn't start. It was a fresh battery so i figured my alternator is bad. I don't have a voltmeter in it so i couldn't tell if it was charging. I took the alt off and took it to pep boys where they spun it and told me it was bad.

So then I switch to a 1-wire alternator and hooked everything up including a new Voltmeter and it still only showed about 12.5 Volts at idle. Shouldn't it be showing like 13 at least? And then go up to 14 when I rev it up?

If anybody can help i would appreciate it.

Thanks,
Iggy

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[jeff]

Iggy,

On my 1993 Cherokee with 193,xxx miles the volt meter never reads near 14 at idle and rev'ing it up doesn't produce a visible change. I think the idiot gauge in my Jeep isn't worth the space it takes up as I know my alternator is charging properly. Checking the alternator at it's output with a multi-meter is probably what you'll want to do to ensure it's actually putting out the juice it needs to.

Aloha

[scottm]

Yes it should go over 14 volts when first started, and never drop below 13.5 when running.

[Iggle]

Iggy,

On my 1993 Cherokee with 193,xxx miles the volt meter never reads near 14 at idle and rev'ing it up doesn't produce a visible change. I think the idiot gauge in my Jeep isn't worth the space it takes up as I know my alternator is charging properly. Checking the alternator at it's output with a multi-meter is probably what you'll want to do to ensure it's actually putting out the juice it needs to.

Aloha

Yeah i think that's what i should do. I disconnected the positive terminal on the battery while the jeep was running and it didn't die so i'm assuming the alternator is working and it was running off the juice it was producing when I disconnected it. I'm gonna invest in a nice multi meter and follow your advice.

Any idea on why the voltmeter only registers 12.5 volts? I don't get that.

[jeff]

I've got a lot of questions about how Jeep put my Cherokee together.

All of the current for the power door locks goes through the front passenger side door. My locks are a little slow to operate if the Jeep hasn't been run for a while and the battery voltage is a low and it's cold outside (winter). If I use the passenger side switch more power goes to the lock mechanisms and everything opens up. If I use the driver switch the resistance is just a little greater and it won't unlock the doors. Why not route all the power through the driver side switch? I mean, most of the time I'm driving from the driver side and not the passenger side.

The wiring that goes under the footwell on the driver side. Frequent in and out + wet boots caused wiring under the carpet to short out. Why Jeep didn't route it away from the footwell is beyond me. I guess the shortest run was the cheapest run. I had to cut/splice the wires back together and wrapped the heck out of them to prevent the same from happening again. Spending a buck here on the assembly line would have prevented this from happening.

Crap headlight wiring. Have you ever checked the voltage at the headlamp bulbs? Rewiring the factory mess (properly) makes the difference between brown light and white light. Again, cheap for Jeep to do during assembly but they neglected it and the consumer ends up with dim lights.

Neutral / Reverse switch in the trans. Clean it works. Dirty it prevents the engine from being started. I bypassed mine and don't care if the computer gets mad that it can't figure out what gear the trans is in. Reverse lights mean nothing if the engine can't be started. Jeeps are touted as capable off-road vehicles... a Jeep that can't start isn't much good to me. Replacing this part is EXPENSIVE. Cleaning it properly works for a while then it poops out again. Another poor design... why?

Temp Gauge - mine sometimes reads VERY HOT but using an infrared temp gun right at the sensor itself suggests it's actually running cooler than the gauge suggests. I've read up on this online and other people have spent more time researching this than me and they had the same results. I guess it's better to read warm and actually be running cooler than the other way around.


Back to the alternator... if you go back to Pep Boys have them test the alternator while the Jeep is running. Most of these places have a small hand held tester that can be quickly attached to ground & alternator output to verify the voltage output is correct. My guess? It'll be 14v-ish at the alternator and everything is AOK. I have ZERO faith in my factory volt gauge.

Aloha