gmman,
In your third paragraph you mention FM and PM. Please excuse my ignorance of acronyms, but what are they?
Regarding your last thought the 14.42 volts at the battery was the reading I got upon cranking the motor with the hand held volt meter connected to the battery and observing both the hand held volt meter and the IC volt meter simultaneously. The hand held read 14.42 and the IC meter read 12 to 13 for about 30 seconds and dropped to 8 volts and stayed at that reading while the hand held meter continued to read 14.42 volts.

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LocoWBL

PM is for private message used by members to transact situations not suitable for general viewing.

FM was my idea of a funny that upon further review was not funny. in working around electronic circuits often they will defy logical analysis. so in trying to explain the unexplainable we sometimes use the term f---ing magic (FM). sorry for the confusion.

getting back to your latest check that confirmed IC voltmeter is 8V when battery is 12-14V, am convinced that your battery and alternator are ok. so no need to do the external wire check. it appears that the tachometer is in parallel with the voltmeter as far as voltage source is concerned. so once again it would appear that the problem would have to be in your IC voltmeter circuit (i am assuming that you have not seen any problems with tach operation). based on 96 configuration (2000 may be significantly different), i would next change out the Instrument Cluster.

my attempt to rationalize this development, the IC voltmeter is ok (reads 12V for an indefinite period) with just the key in run, engine not running. but if you start the engine, 30 seconds later the IC voltmeter drops to 8V. so apparently something about increased voltage (approx 14V because alternator is functioning) is causing IC voltmeter to drop. so once again be sure your tach is reading ok because tach and voltmeter are fed from the same source (in 96). if the tach is ok, still looks to be bad voltmeter.

here is 96 IC voltmeter schematic. you can see that voltmeter is in parallel with other gauges so if other gauges are normal it would seem that voltmeter is bad. however, don't know if 2000 is configured similarly.

Gmman,

Don’t worry about the confusion. I think we’re all in need of a little humor especially in this day and age.

I haven’t noticed any real problems with the tach. It does seam to read about 150 rpm’s higher at 70 mph than I remember, but it has been doing that since the motor and transmission overhaul six months ago. I’m only assuming that it’s because the transmission shop replaced the torque converter and it’s slightly different from the factory one.

I don’t know if this is or isn’t related to the malfunctioning volt meter or not, but the security light on the IC occasionally comes on when I start the car and stays on. Sometimes if I shut it off and restart it will disappear and stay off for several days or a week. Sometimes like this morning it didn’t. I guess now all there is to do is wait for the IC that I ordered to come in and try that and see what happens next.

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LocoWBL

yeah, i think replacing the IC is the next step. however, it will be important to verify that gauges other than voltmeter do not change after 30 seconds. might pay to start the car and watch the other gauges, at the time that the voltmeter drops, check that other gauges are still same. reason being that other gauges (tach and temp) are in parallel with voltmeter and share the same voltage source. want to make sure that whatever causes voltmeter to drop doesn't affect tach and temp. if they do vary, it could mean that voltage to the IC is dropping. i would no longer suspect the alt or batt, however.

edit: don't think that other problems you noticed (small tach difference at 70 and security light) are related especially if it turns out to be faulty IC voltmeter.

Well guys it looks like I’m back to square one with this issue. My IC panel came in and I put it in last night. It does the same thing as the old one. The only difference is it shows about 38k less miles than mine so the voltage issue still remains. Anybody need a spare IC panel? LOL

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LocoWBL

hate that! looks like point to point wire/connector, voltage/continuity checks next. don't know if my 96 schematics are close enough but will work up some ideas. if you find that wire colors, connectors or pin numbers don't jive with what my 96 shows, will have to get some info from members with later model FSMs.

be back with some ideas soon.

which instrument panel do you have? for 96 there is an option of UB3, U50 or U2F. i am only familiar with analog gauges. are yours analog or digital?

edit: note the difference in UB3 and U50/U2F in the image below. there is a solid state component to the voltmeter gage and a feed to starting and charging. i am trying to chase down the source of this feed in the event that you have this type of IC.

just reread entire post on this subject and concluded that your IC/voltmeter circuitry is probably very different than my 96 (finally noted that you say voltmeter "sweeps"). i don't think i can help with this handicap. was very interested in seeing you resolve this and will check future posts to see what you find.

Yeah it’s a frustrating problem for sure. All of the gauge needles sweep when I fist crank the motor up. I think it’s a self check before settling on where the need to read. I don’t know why, but I keep thinking back to when this whole problem originated and I remember hearing the fuel pump cut on for a few seconds and at the same time the volt gauge needle would drop. I don’t know much about electrical issues and maybe this is purely coincidence as for the pump running and the needle dropping, who knows. Anyway the pump has been making noise on and off for quite a while so I’ve been wanting to change it, I just didn’t want to drop the big bucks for the Delco pump but maybe it’s time to try that.

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LocoWBL

Well guys as willwren stated the fuel pump wasn’t the reason for the volt gauge malfunction. I replaced the pump and still have the same problem with the volt gauge.

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LocoWBL

Mine started do the exact same thing today after I ran through 4 inches of rain water.