Voltage guage Problem

My voltage guage is reading up in the red section(charging), but the output is still within specs. The XJ was involved in a minor frontal crash and some of the engine front components got replaced. I tightened the belt, but even the Chrysler mechanic that looked at it said that it was performing within specs. It's a '94 sport with a 4.0. Can anyone tell me what's up?? Thanks


Jeff

The voltmeter in the IP is a notorious liar. If you're nominal, make a mental note of where the needle runs, and call that "normal."

I'm running right around 14.4 - but my voltmeter is on the lower edge of the upper red. Always has been.

I plan on redesigning the IP anyhow.

5-90

If the vehicle suffered an impact, it probably affected the meter. Here's the deal:

This meter is a pretty primitive piece of work, and it is calibrated by the location of a small magnet which is glued into its case. The glue is brittle. If the magnet gets dislodged, it becomes wildly inaccurate (this in addition to the inherent inaccuracy of the circuit that feeds it). The magnet doesn't actually fall out, because the case itself is steel. So what you need to do is to take out the cluster, take out the voltmeter, open up its back, and try to reglue the magnet in the proper locationo on the inside of the back. You'll have to experiment, but the calibration basically is done by moving the magnet forward and back in the case. You can use a sticky glue like shoe goo, or prehaps a tacky craft glue, to hold it in place when you get the right value.

You can connect wires to the naked voltmeter, and use your battery or some other source whose voltage is known accurately, and adjust it that way.

Once it's calibrated, it will still lie when you turn your heater fan on high, but it will do it with some consistency.

My gauge was reading wrong after i did the full dash swap..i ran a ground wire from the IP voltmeter through the firewall to the firewall ground bolt in the engine compartment, then ran a wire to an empty slot in my fusebox...works like a charm13.8-14.2 volts..im no electrical engineer..(im a surveying engineering student)..but holy crap it worked

The volt meter in the instrument panel is a liar. I have noticed that i shows less when it is hot outside (summer time), than in the winther. In the winther it shows almost correct value.

Torfinn

torfinn said:

The volt meter in the instrument panel is a liar. I have noticed that i shows less when it is hot outside (summer time), than in the winther. In the winther it shows almost correct value.

Click to expand...

Later model vehicles the PCM controls the alternator/generator field strength and varies the charging voltage according to the battery temp. In colder temps it should set a higher voltage, within the normal operating range, and in hotter temps it should set a lower voltage also within the normal operating range.

If you have a battery temp sensor, touching or near the battery, usually in the battery tray, then you most likely have this feature as part of the electronic engine management.

Hey,

What does "IP" mean? Impedence?

btw- I ran a new ground from the battery to the firewall and now the Voltmeter doesn't fluctuate as much when the blower fan is turned on.

Thx, Phil

instrument panel