2nd Gen Non-Engine/Transmission voltage gauge

[Tractorat]

I started up the road yesterday. Just after I got on the freeway the check gauges light and chime came on. When I looked at the gauges I saw the voltage gauge had gone to zero. My first thought was crap, the alternator is toast. So, I took the first exit and went home. When I got home before I shut the engine off, I put a voltage meter across one of the batteries and got 14 plus volts. So, the alternator is working. I shut the engine off and measured across the battery and got about 13.5 volts which is what I expected. So, I put the key in the run position and the needle on the gauge moved up to about 12 volts (I guess). So I restarted the truck and 30 seconds to a minute later the needle was back where it should be at about 14 plus volts. So, I went on my little trip north about 70 miles with no more problems. I came back again this morning with no problems.

Any idea what could cause that ? If it was a computer glich, can I expect it to happen again ?

Oh, I may have heard a slight pop just before the needle went to zero, but Im not sure of that. I also may have smelled a slight burning plastic smell after driving north yesterday, but not enough to be sure. I looked under the dash and did not see anything that looked burned and I didnt feel any excess heat.

 

[crabman]

Look at the wiring that is attached to the alt and follow it to see if is chaffing and/or a loose connection. If you heard a slight pop & smelled a slight burning odor, then something some where is grounding out.

 

[Tractorat]

I think the alternator is OK. Even though the gauge was showing zero voltage, I was getting 14.2 volts across the battery. I think its in the dash. Either the cluster or the actual gauge.

 

[phantomusa]

If you have looked everything over and don't see any areas that mite be shorting out all I can say is you can't fix something that's not broken quirky little things do happen on vehicles that all just magically fix them self and never happen again
My advise is drive it until something is broken they you'll have a item that needs fixin
Pappy

 

[Road Dog]

All the guages in the cluster are electronic -- they receive and display data from the ECM. If you want to see the actual voltage then you need to connect a volt meter to some thing like the power port on the dash.

 

[Tractorat]

All the guages in the cluster are electronic -- they receive and display data from the ECM. If you want to see the actual voltage then you need to connect a volt meter to some thing like the power port on the dash.

The gauge reads fine. I just wondered if it was normal to take so long to come up to the normal reading.

 

[Tractorat]

Did it again today. This time I checked for codes (key click). I got a P1682 and P1693. Bad alternator ?

 

[GAmes]

If you shut it off, wait a few seconds and restart does the alternator come on line? When I forgot to turn off my grid heaters (I have them on a toggle) it overloaded the alternator and the PCM shut it off, which I am sure is a built in feature. Turning off the grid heaters wasn't enough, I had to shut off the engine to reset the PCM. I suggest you pull the trigger wires off the grid heater relays and see if that fixes it. One or both relays could be sticking.

 

[Tractorat]

If you shut it off, wait a few seconds and restart does the alternator come on line?

Well..., I dont think the alternator is going off line. The voltage gauge on the dash board will say zero. But if I pull over and put my voltage meter across the batt terminals, I am getting 14 plus volts which makes me think the alternator is doing its job (?). And, yes. If I shut the engine down and restart, the voltage meter wakes up as soon as I put the key in the run position and reads correctly when the truck is running as well.

 

[Missouri Mule]

Seems like your voltmeter is acting up.
Code for alternator is probably popping up because of voltmeter dropping. If it is like the 2nd 12 valves there is a asd relay in the pdc that sends line voltage to pcm it mite be acting up. The asd relay mite send line voltage to gauge or the pcm/evr does.

 

[Tractorat]

I got a digital voltmeter that goes into the cigarette lighter so I can monitor the actual voltage. It does drop to 12v when the alarm comes on. I dont think I drove it long enough this last time to see if it comes back up on its own before I stop and checked it at the batt. Im starting to lean toward the alternator.

 

[Missouri Mule]

Do not remember when they dropped the pcm (had one in the 98.5 and 99 along with a ecm).
I check the battery temp sensor under driver's side battery tray, if it is acting up it could cause the electronic voltage regulator to have the alternator reduce the voltage output.
I once pulled the asd relay out to see what would happen. The voltmeter was reading the same voltage. 7