Dome Light And Instrument Cluster Back Lights

[David Klinner]

I am new to the Mustang family. Last Friday traded my 2005 Triumph Rocket III Cruiser for a beautiful 2002 Mustang GT 5-speed manual with the King Cobra clutch... or so I've been told. The car has recently been gone completely through. Newer Lincoln 4.6L engine installed, all new suspension. After a week of playing with the car I've installed the MSD coil packs, and have enjoyed driving the car. However my dome light, map lights, and back lights for the speedometer and tach will not work. The red lights for the needles and the lighting for the surrounding guage also work buy will not dim with the headlight switch. It does have an aftermarket radio installed improperly by the previous owner. All other items are in working order. Replaced all fuses with new ones and still no joy with dome light, map lights and back lights for speedometer and tach. Any suggestions?

 

[wmburns]

We need to know IF there's power in/out of fuse F2.37 with the headlights on and the dimmer turned all the way on (past the click).

1999-2004 MY fuse panel schedule:
http://www.allfordmustangs.com/foru...r-swap-wont-fire-please-help.html#post2669271

Where to go next depends on IF there's power in fuse F.27

 

[David Klinner]

Alright then, I'll have to check that when I get home from work, or tomorrow. Like I said everything else seems to be powered and working properly. The only questionable issues might be with the improperly installed aftermarket radio.

 

[David Klinner]

Just tested the F2.37 and do have power, replaced the fuse also just to be on the safe side... This is also what I've noticed... The radio will not hold presets... won't have time to fool with that till the next weekend... Fog lights do work, however drivers side is blown... the buttons light up for the fog lights, and for the back defogger, however not for the traction control and last problem I've discovered is backup lights do not work... an external oil pressure gauge was installed because last owner couldn't get gauge in the cluster to work... trying to think of anything else... Oh when the AC is on will not idle properly... AC system may need to be charged though... I have read about that issue and it does idle correct when AC is off.

 

[wmburns]

IF there's power in fuse F2.37 but the lights do not work THEN:

• the light is bad
• the Ground is bad.

If this were my car I would test the ground's ability to carry current back to battery negative.

Here's some information on how to perform voltage drop tests. This will confirm one way or the other if the failing device has a working ground.

Note the "howto" describes how to test a charging system. However the same theory applies to testing any ground. IE put one VOM lead on the supply at the device to be tested. The other lead on battery negative. In a working circuit this will give the voltage drop across the circuit.

Note2; in a working circuit the voltage will never be zero when there is current flowing. No circuit is perfect. If the voltage is zero then likely there's something wrong like no current at all.

Note3. also not a bad idea to confirm power at the device itself. Use a KNOWN good ground.

Howto perform charging system voltage drop test
https://www.stangnet.com/mustang-fo...perform-charging-system-voltage-drop-test.56/

 

[David Klinner]

Okay, it may be a ground issue, or the original owner may have neglected to connect absolutely everything. The car was painted and all the interior updated. It all looks brand new. Working 2nd shift puts a strain on working out these bugs. I will check the things you've suggested. It's just a bit frustrating drive at night without seeing the speedometer. Too easy to speed in this car... thank goodness for cruise control, and a mini flashlight. Will let you know what I find out.

 

[Neuron]

.. The radio will not hold presets...stem may need to be charged though... I have read about that issue and it does idle correct when AC is off.

There should be a wire from the radio that is supposed to be hot all of the time so when you turn the key off it doesn't lose memory.