Electrical Gremlins Got Me Tonight HELP!

[Nickisa0]

I had my girlfriend swapping my dome lights to LED's and she says "while I was backing the screws out the dome light went off" and since then I haven't been able to get them to come back on. I tried swapping back to the regular bulbs and it didn't change a thing. I figured I would just deal with it and fix it later. I went to install LED's into my HVAC panel and realized I didn't have my torx wrench with me. So I reassembled everything and started the car and drove home. On my way back home I immediately noticed my aftermarket cd player and speedometer were nolonger working. I was instantly frustrated, when I got home I tore back into my dash to see if wires were messed up. I search for a good 30minutes and couldn't find anything wrong with my wiring. Then I went ahead & installed LED's into my gauge cluster, it went smoothly. I put it all back together and then I noticed that my tach nolonger worked... Now I noticed that my unlock/lock buttons, power mirrors, door chime, keyless entry, remote trunk release nolonger work. When I press the "unlock" button in the inside of the car my signal lights come on.

List of what isn't working:
Aftermarket cd player
Dome light/map lights
Speedometer
Tach
Unlock/lock buttons
Mirror buttons
Keyless entry
Remote trunk release
Door chime

I have no clue what's going on here, I just know everything worked perfectly up till an hour ago! Where do I start? I checked the fuses and they all came back to be fine. So what do I do now?! For reference I have a 1998 Mustang GT.

 

[Nickisa0]

I was hoping to wake-up this morning and have a handful of things to check.

 

[nyuk98gt]

Nickisa0:

Everyone is still sleeping or driving around?

Check your fuses (with an ohm meter). There are two fuse panels - one on the lower LH underside of the dash and the high current panel in the engine bay. I suspect you have one or two blown or there is a bad connection somewhere.

From my own experience, I have learned to disconnect the battery before doing any electrical work. I am not a very good electrician but I don't blow stuff up too often.

HTH,

Chris

p.s.-- Welcome to StangNet.

 

[Nickisa0]

Nickisa0:

Everyone is still sleeping or driving around?

Check your fuses (with an ohm meter). There are two fuse panels - one on the lower LH underside of the dash and the high current panel in the engine bay. I suspect you have one or two blown or there is a bad connection somewhere.

From my own experience, I have learned to disconnect the battery before doing any electrical work. I am not a very good electrician but I don't blow stuff up too often.

HTH,

Chris

p.s.-- Welcome to StangNet.

I already checked both fuse panels. I did some research and somebody was having the same issue and it was blowing the #8 fuse. I triple checked that one and it's fine. I checked all my fuses with a fuse tester (light comes on if it's good) and they all were fine.

 

[n0v8or]

It's not clear from your original post over what time period all of theses problems developed. Can you elaborate?

You mentioned operating the "unlock" switch turns on your "signal lights". Do you mean the turn signals, at all four corners? Do they appear to be at full brightness? Does this happen with the passenger door unlock switch as well? Does operating the "lock" switch produce some unexpected reaction?

When using a test light to check fuses, the key must be in the ON position and the fused device must be turned on. Otherwise, you may get a false reading.

Does your Mustang have lighted vanity mirrors in the sun visors? If yes, are they working?
Are your intermittent windshield wipers working?

 

[Nickisa0]

It's not clear from your original post over what time period all of theses problems developed. Can you elaborate?

You mentioned operating the "unlock" switch turns on your "signal lights". Do you mean the turn signals, at all four corners? Do they appear to be at full brightness? Does this happen with the passenger door unlock switch as well? Does operating the "lock" switch produce some unexpected reaction?

When using a test light to check fuses, the key must be in the ON position and the fused device must be turned on. Otherwise, you may get a false reading.

Does your Mustang have lighted vanity mirrors in the sun visors? If yes, are they working?
Are your intermittent windshield wipers working?

I would say over a period of about 30minutes I noticed this stuff wasn't working. As for the unlock button... I just double checked it all and here's what I've come-up with.

Pressing the "unlock" button of both the passenger & drivers side will set-off the front amber blinkers, rear blinkers & tag lights. They seem to be full brightness and I can also hear something clicking around the trunk around when I do that. Maybe a fuse or something? Nothing happens when I press the "lock" button on either door.

To test the fuses I used a yellow fuse tester and the key was not in the car. I also visually inspected them and they all seem fine. When using the test the green light came on for all of them, so that means they were fine.

My car does not have vanity lights in the mirrors.

I just went out & tested the windshield wipers... They work fine, but when I press the "spray" button I can hear a loud electric motor sound. I would assume that's the pump for the nozzles although I don't recall ever hearing that before.

Thanks for your help, I really do appreciate it. Nobody has seemed to even try and help me out yet. I wish a local guy was around here that I could get to look at the car. I understand it's a PITA to try and explain stuff over the internet and get a solution. So THANK YOU!

 

[n0v8or]

OK . . . that info helps.

It sounds like, with the exception of the non-functioning dome light, all of the other problems happened approximately together. This suggests the possibility that several or all problems have a single cause. Is the dome light problem also included in the 30 minutes, or did it stop working much earlier?

I can only think of one module that is common to interior lights, exterior lights, door locks, trunk release, chime, and keyless entry: the RKE module (which I think is located in the trunk, perhaps below the package shelf). The RKE is probably what you hear when operating the unlock switches. The tach, speedo, mirrors and radio remain a mystery for now, and may have a separate cause related to removal of the instrument panel.

What I would do in a case like this is concentrate on just one thing, and hope everything else sort of falls into place.

Another question: does the manual trunk release switch work? If yes, it means the circuit breaker (not a fuse) that feeds the RKE module is probably OK. If not, I would try a new breaker. I suspect the breaker is OK, given the RKE is able to power the lights.

I would not discount fuse #8 without first replacing it with a new one. It is the one fuse most likely to have caused most of the problems you described, and could have been compromised while working on the dome light with the battery connected. I don't trust a test light, or visual inspection, to check fuses; I can think of several ways the light could be fooled (such as not having a load on the protected side of the fuse).

Another possibility is a fusible link failed. But if this were the case, your test light, if connected between the battery side of each fuse and ground, would fail to turn on at multiple fuses (ignition must be on for this test). Can you describe how you actually use your fuse tester?

 

[Nickisa0]

OK . . . that info helps.

It sounds like, with the exception of the non-functioning dome light, all of the other problems happened approximately together. This suggests the possibility that several or all problems have a single cause. Is the dome light problem also included in the 30 minutes, or did it stop working much earlier?

I can only think of one module that is common to interior lights, exterior lights, door locks, trunk release, chime, and keyless entry: the RKE module (which I think is located in the trunk, perhaps below the package shelf). The RKE is probably what you hear when operating the unlock switches. The tach, speedo, mirrors and radio remain a mystery for now, and may have a separate cause related to removal of the instrument panel.

What I would do in a case like this is concentrate on just one thing, and hope everything else sort of falls into place.

Another question: does the manual trunk release switch work? If yes, it means the circuit breaker (not a fuse) that feeds the RKE module is probably OK. If not, I would try a new breaker. I suspect the breaker is OK, given the RKE is able to power the lights.

I would not discount fuse #8 without first replacing it with a new one. It is the one fuse most likely to have caused most of the problems you described, and could have been compromised while working on the dome light with the battery connected. I don't trust a test light, or visual inspection, to check fuses; I can think of several ways the light could be fooled (such as not having a load on the protected side of the fuse).

Another possibility is a fusible link failed. But if this were the case, your test light, if connected between the battery positive side of each fuse and ground, would fail to turn on at multiple fuses (ignition must be on for this test). Can you describe how you actually use your fuse tester?

Well I first noticed the dome light didn't work because that's what I was working on at the time. I just gave-up on that and then went to work on the HVAC panel & gauge cluster lights afterwards. So I started to slowly notice the other things weren't working shortly after that. I NOW HAVE THE TACH WORKING, I just pulled the 3 pods off the gauge cluster double checked everything and re-installed it. I took it for a drive hoping the speedo would work also, but it did not.

I just had my girlfriend go out and try to open the trunk from the button inside the glovebox and it works.

Here's the fuse tester I've been using:

It has a small green LED on the other side that will light up when the connection is complete I guess. It's pretty much the basic one you can find.

I'll pick-up a pack of fuses tonight on my way home and change #8 just to make sure. Thanks!

 

[n0v8or]

I understand about the fuse tester now. It has a battery and a bulb (or LED) inside. If the two probes are shorted together (such as by the two terminals of a good fuse), a connection is made between internal battery and bulb/LED, and it turns on. What it doesn't tell you is if power is reaching the fuse from the battery. Some circuits are double fused, plus there is the "fuse of last resort" (the fusible links).

If there is a Harbor Freight near you, they sell a cheap (but good enough) digital multimeter for ~$3. Probing each end of the fuse, with the black probe connected to chassis, will tell you if battery power is reaching the fuse and passing through it OK. You can use the resistance (ohms) scale to test both fuses and circuit breakers (the fuse tester can't readily test breakers unless you can adjust the probes to match the spacing of the breaker terminals).

 

[Nickisa0]

I understand about the fuse tester now. It has a battery and a bulb (or LED) inside. If the two probes are shorted together (such as by the two terminals of a good fuse), a connection is made between internal battery and bulb/LED, and it turns on. What it doesn't tell you is if power is reaching the fuse from the battery. Some circuits are double fused, plus there is the "fuse of last resort" (the fusible links).

If there is a Harbor Freight near you, they sell a cheap (but good enough) digital multimeter for ~$3. Probing each end of the fuse, with the black probe connected to chassis, will tell you if battery power is reaching the fuse and passing through it OK. You can use the resistance (ohms) scale to test both fuses and circuit breakers (the fuse tester can't readily test breakers unless you can adjust the probes to match the spacing of the breaker terminals).

I have a couple multimeters here, I just never bothered to get them out since the tester was working. So I'll bust that out tomorrow sometime and check my fuses, mainly #8 How much should be showing up when I probe the fuses? Just to make sure I should do this while the key is in the ignition and in the "on" position correct? Sorry about my electrical ignorance, I really hate this stuff!

 

[n0v8or]

According to the drawing I have (Haynes manual, not official Ford), the RKE module has 3 separate power feeds.
A circuit breaker - this is probably OK since the manual trunk release works.
Fuse 6 - this feed is only powered with the key on.
Fuse 8 - this is powered at all times, even with the key off.

Connect the negative meter probe to an unpainted chassis ground point.

Touch the positive probe to one end of the fuse, then the other (same points contacted by the fuse tester). Both should read the identical voltage, typically in the range of 12V-13V for a fully charged battery.

f there is voltage at both ends of the fuses, the logical next step would be to probe the wires to and from the RKE module. It's possible the module was accidentally damaged, or a ground wire is broken. It might be easier to try to find a spare RKE module at a wrecking yard, and then swap it with yours. If the replacement RKE module works, the remote will have to be reprogrammed before it will lock/unlock the car.

 

[Nickisa0]

Well I just learned my lesson about visibly inspecting fuses....

Both #6 & #8 looked just fine, I popped new ones in both of them and instantly the door chime and the radio popped on!

I LOVE YOU :SNSign:

 

[n0v8or]

Those old fuses might not necessarily be bad. I've found that, after ~10 years of hot/cold/humid weather, corrosion can degrade the connection between the fuses and fuse panel sockets. Simply removing and replacing the same fuse is sometimes like magic. A little cleaning with fine sandpaper, and a light coating of conductive grease on the fuse terminals, and you're good for another 10.

If you are lucky, the fuses protected your RKE module from damage.