Mopar_Aaron

I just put it in a new alternator and battery and the volt gauge is reading 11 volts. I know the grid heater cycles on and off for awhile it's been very cold here in nyc. At what temp does the grid heater stop cycling. I Checked the ground to alternator everything was fine. Charging issues or normal behavior for these first gens? Can the ksb be the issue?

cougar

Don't rely on the instrument panel gauge to give you an accurate reading. Put a volt meter on the battery while it is running. It should read about 14 volts. The heater grid is on a decreasing cycle timer. One the grid heater starts, the off time increases as the on time decreases. Charging issues are common especially with 92s and 93s. A "no charge" situation could be anything from a bad auto shut down relay to fried fusible link. In any case, you are not getting 12 volts to the alternator field winding.

Mopar_Aaron

I put a volt meter on the battery and it read at about 11.7 volts thought that this was normal range for the truck with grid heaters cycling?

Comrade General

Not sure about during grid heaters but thats low.

jimlj

If it were grid heaters cycling your voltage would cycle as well.

cougar

Correct.
Typically, when the grid heater cycles on the voltage will drop to around 9 volts (at least on my truck it does). When it cycles off, it's back up to 14 ish. It will continue to do that until it completely cycles out.
So, if it goes up to 14 ish when the grid heaters are off it's good.

Mopar_Aaron

Well my truck for some reason has an aftermarket ignition so when I turn the key to the on position all of my lights on the display come on; water in fuel, wait to start....etc. but the the truck was wired to start via a push button on the lower dash. I know when it's cold out that the wait to start light will come on and stay lit for a few seconds, but mine doesn't. As soon I as I turn the key from on to run and the wait to start doesn't stay lit. I don't know when the grid heaters come on. The truck does start right up in 20 degree weather, but the volt meter stays at a constant 8 to 11 volts and never goes higher. I thought that the heaters would keep the voltage at a constant low. It never goes from 8 to 14 volts. Any ideas what's going on? Going to put the stock ignition on helps that solves the problem. If it doesn't then I don't know what's going on.

snowjoker

Run the truck a little while till its warmed up then check the voltage. I had charging issues too. Killed a brand new battery in less than month. So i put in new battery and still was only running 12.5 volts running, new voltage regulator... same.. New alternator 14.8 - 15 volts now right where its supposed to be

Mopar_Aaron

I just put in a new alternator and battery a few days ago and no difference

j_martin

There are several things that have to be right for the alternator to work. At this point it appears you have a haywired ignition system, probably the grid heaters aren't working, starter circuit bypassed, and who knows what else.

Back to the alternator. If your truck hasn't been retrofitted with an external voltage regulator, the PCM (Powertrain Control Module) does the job. It needs two power feeds, one direct, and one from the ignition switch to start up. then it needs a signal from the CPS (crankshaft position sensor) to tell it to start the alternator and other systems. (Tach, OD, etc)

At the alternator, Engine off or on, it should have battery voltage at the large stud. If not, a fusible link is bad. Engine running, it should have battery voltage on one of the small studs, supplied by the shutdown relay, and the other should be pulled to ground more or less by the PCM.

Normal charging voltage is around 14 Volts. The grid heaters draw almost twice as much as the alternator will put out, so it's normal for them to pull the battery way down when they cycle. They normally turn on for a few seconds, and never stay on solid. From your description, it sounds like the PCM is missing a temperature signal and never cycles them, or there is another fault with the controls.

It's a Cummins. It'll start without the grid heaters down to about 0, but it will complain about it with smelly unburned fuel from the exhaust.

Mopar_Aaron

Thanks what you said makes a lot sense. I'm trying to get the ignition issue this weekend. And get rid of that push button start. Are there any write ups on checking the pcm for issues you stated? Thanks I really appreciate the help. Also you said these Cummins will start without grid heaters. Would a grid heater delete be something I can consider?

j_martin

Spend some time in the stickies. Among other things there's a link to the wiring diagrams out of the FSM for your truck.


I'd run the grid heaters unless you're drag racing or something. Pre-heating the air takes a lot of the fuss out of starting it and running for the first few minutes. It'll also allow it to start at a downright obscene temp.

Mopar_Aaron

True. Thanks for the help. And I appreciate your post on my other thread.

Mopar_Aaron

Still no charge guys. I was reading some stickies and found out that I can switch the ac relay, or starter relay to test the asd? But how do I properly check the cps? I don't want to have to buy a new cps or pcm.. also read that if the ac is working that the pcm is fine? Need some help really want to get this charging issue under control. Put in a new alternator and battery and changed out the battery terminals as they needed replacing. Also put in a new belt and tensioner. What should I test next? Grid heaters are not coming on. I have an aftermarket cylinder key lock didn't get to put the stock one in yet. But this charging issue is driving me crazy.

jimlj

i don't know if your '92 is the same as my '89 wiring, but here is the wiring diagram I used when installing the engine in my Ford.