94 Mustang V6 Manual Running Rough Gauges Erratic

[mike boyce]

Car has been running fine. Pulled out of driveway this morning and car fully died. Tried to turn the key and had no power to anything. After a few moments It started, however the guages were erratic. Tach fluctuates from 0 to 1500 RPM with no idle change. Temp is pegged but engine is cool. Volts are pegged. Car started ran for a minute then died again. Snow it is barely running and guages are still all over the place. Battery is brand new. I replaced the ignition cylinder lock as it was shot, thought may have been the problem. Still nothing. Could a bad alternator cause this?

 

[General karthief]

I think this needs to be moved to the tech threads so you can get some help.
And welcome to stangnet

 

[mike boyce]

UPDATE: I also checked the alternator and its.putting out 14.65v.
When car is running the guages (temp, oil, battery) will jump when any added draw is put on the electrical system, such as radio, lights etc.

 

[General karthief]

I'm not up on the 94-5 model electronics, they differ from the fox cars in many ways, I am doing a little research on this but in the mean time I can tell you to check your electrical connections, mainly the grounds, has there been any work done to the car like upper/lower intake removal or upgraded anything?

 

[mike boyce]

I'm not up on the 94-5 model electronics, they differ from the fox cars in many ways, I am doing a little research on this but in the mean time I can tell you to check your electrical connections, mainly the grounds, has there been any work done to the car like upper/lower intake removal or upgraded anything?

 

[mike boyce]

No recent work done. After further diagnosis there is a short somewhere.

Car Running:
14.65 volts at battery
.04 volts negative battery post to engine
5 volts negative battery post to body
5 volts engine to body

 

[General karthief]

Well thats not good.
Check your connections starting at the battery, I believe that model has a ccrm, and is obdll, see if you get any codes, I dought it will help but my knowledge on these are sketchy.
Maybe @jrichker can offer some incite

 

[Dan_Soprano]

I'd take the alternator off and have it checked at a local parts store. Most will test and check for free.

 

[mike boyce]

So, somewhat narrowed down. Disconnected neg cable from battery. Connected a test light from neg post on battery to neg cable and started pulling fuses. Pulling the 50a Hd. Lps fuse caused light to go out, indicating this circuit is the source of the short. Now I'm trying to find the easiest way to pin point the short. Any advice would be greatly appreciated.

 

[General karthief]

What is hd. lps?
I'm try'n to acquaint myself with this model.

 

[mike boyce]

Underhood fusebox Head Lamps fuse

 

[mike boyce]

Hit send too fast. That fused circuit includes: headlamps, Airbag module (aux pwr), key-in ignition chime, courtesy lamps, glove comp. Lamp, power mirrors, radio, instrument cluster, clock, trunk lamp, anti-theft doir open signal, flash-to-pass, low beams, exterior lamps, deck lid release, and door locks.
All of which are operational.

 

[General karthief]

Those are powered all the time I think.
I went back and read your post again, possible ignition switch problem? Not key switch.