Intermittent volt meter

Hi,
The volt meter drops to 0 and the gauge warning comes on about 5 min after starting the engine. This just started a couple of days ago. All else is working, although the speedometer needle flipped around a couple of times yesterday, but behaves normally since then.

Is this a known issue? What are the highest probabilities? volt meter, wiring, regulator, alt., a relay?

1999 Sport, 4.0L I6, 5 spd. 4X4.

Glen

Re: Intermittent ammeter

These Jeeps don't have ammeters from the factory. Are you speaking of the volt meter?

Re: Intermittent ammeter

Doh, correct, it is a voltmeter

glen

If you have access to a multimeter I suggest using it to check whether or not it's a gauge or alternator issue. Unfortunately Jeep used "semi-dummy" gauges on these vehicles. i.e. If the voltage gets "low" (under ~12VDC) the gauge doesnt' read actual voltage, but instead reads 9v (minimum). (the same is true for the temperature gauge and temps above 220).

Check voltage with a meter at the battery, while jeep is off it should be 12-12.5 ish and while running it should be 13.5-14 ish.

If all of this is good, even after the volt meter drops to zero, it's a volt meter, or gauge cluster connection problem.

If the voltage is indeed low <12 while running there are a few things to consider with the 1999 year model.
1. The alternator.
2. Wiring from alternator.
3. Battery temperature sensor (mounted in battery tray, plug is on fender right next to battery)
4. PCM (not as likely)

Start with the cheap/easy/common sense solutions.

Begin with basic trouble shooting of the start and charge systems. Remove, clean, and firmly reconnect all the wires and cables to the battery, starter, and alternator. Look for corroded or damaged cables or connectors and replace as needed. Do the same for the grounding wires from the starter to engine block, and from the battery and engine to the Jeep's frame/body. You must remove, scrape, and clean until shiny, the cable/wire ends, and whatever they bolt to. Jeeps do not tolerate low voltage, bad connections, or poor grounds and the ECM/ECU may behave oddly until you remedy this.

Load Test the battery, test the alternator.

My guess is bad alternator brushes, though it could be some other connection problem.

When this happens next, try rapping on the alternator with a stick or the like, and see if it comes back. If it does it's almost certainly the brushes.

The voltmeter will drop to zero and set the check gauges light if voltage stays below normal for a few minutes. It functions as a sort of back-up idiot light if you don't notice a steady low reading.

Engine off battery voltage is 13 V, running 13.77 V. Great, it's not alternator.
I also noticed this afternoon that the oil gauge was pegged at 80 when the gauge warning light came on and the volt meter dropped. But, tonight, a 30 min. drive and all gauges displaying normal behavior.

Now, I suspect its a matter of cleaning connectors from engine to gauges.

Thanks for the suggestions.

glen

might be a coincidence, or not, but a couple months ago the oil gauge on my 99 4.0l pegged out at 80. so i replaced the sender, all was well for a week. then the voltmeter flucuated from 9-14. a search on here gave me the advice to tap the alternator when it happened, sure enough the brushes had started to give out in it. not sure if a wonky alternator can mess with the special little oil sender but it seems fishy to me.

I think there's also a fairly common problem with the connector on the cluster in this vintage, so if you're getting multiple gauge issues, that's the next place I'd check. I've never had that with my 99, but I seem to recall that cleaning and lubing the connector is the solution. If nobody with experience chimes in here, you might try searching the forum, because it has come up before.

edit to add: when I had the alternator brush problem, it dropped the voltmeter and set the check gauges light, but did not affect the other gauges.

Matthew Currie said:

I think there's also a fairly common problem with the connector on the cluster in this vintage, so if you're getting multiple gauge issues, that's the next place I'd check. I've never had that with my 99, but I seem to recall that cleaning and lubing the connector is the solution. If nobody with experience chimes in here, you might try searching the forum, because it has come up before.

edit to add: when I had the alternator brush problem, it dropped the voltmeter and set the check gauges light, but did not affect the other gauges.

Click to expand...

Correct, Intermittent wacko gauge readings are very common on the 97+ models. The fix is to pull the instrument cluster out and clean all the connections very well. Some seem to have this issue more than others. Personally, i've never had an issue on my 99, but my friend's 98 has had this issue multiple times.

UNCC_99XJ said:

Correct, Intermittent wacko gauge readings are very common on the 97+ models. The fix is to pull the instrument cluster out and clean all the connections very well. Some seem to have this issue more than others. Personally, i've never had an issue on my 99, but my friend's 98 has had this issue multiple times.

Click to expand...

Mine is pretty wacko ever since I replaced the entire interior. I've to tap on mine sometimes otherwise it doesn't read stuff like MPH or RPMs. Like UNCC said, take it out and clean the connectors. I have an issue of my gas meter stop reading once it reaches 1/4th of a tank, so I feel ya on taking off the gauges and cleaning the connectors.

Hey UNCC, want to come help? Ha!

IIRC they do tend to melt and come loose... but this was 3 years ago.

If you are having erratic readings, especially on more than one gauge, I'd start with cleaning the dash cluster connections.

Get yourself a spray can of electronic spray cleaner (available anywhere) and flush the connectors, and be SURE to use a dab of dielectric grease in the connectors when reassembling; the grease is really helpful here.

Good luck!

VestaviaPirate said:

Mine is pretty wacko ever since I replaced the entire interior. I've to tap on mine sometimes otherwise it doesn't read stuff like MPH or RPMs. Like UNCC said, take it out and clean the connectors. I have an issue of my gas meter stop reading once it reaches 1/4th of a tank, so I feel ya on taking off the gauges and cleaning the connectors.

Hey UNCC, want to come help? Ha!

IIRC they do tend to melt and come loose... but this was 3 years ago.

Click to expand...

Yeah I borrowed my buddy's 98 last summer to make a parts run for mine...got about a mile down the road and the gauges were pointed every which way other than what they should have been reading. One of those "what the hell!?" moments

I dont think the issue is so much the contacts melting as corrosion getting on them. A good cleaning and applying some dielectric grease will go a long way with them. If they were melting i'd say you have another issue....

Hahaha..I might could be persuaded to help...but I was thinking last night of all the crap I need to get done on mine in the next month before the Crawl..so I have a feeling my weekends are going to be tied up for a while!