IP Dimmer fuse keeps blowing
08-04-2003, 08:10 PM
#1
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IP Dimmer fuse keeps blowing
I just registered to try and help my father fix this problem on his 94 Z28. I did do a search on "dash lights" and found a few topics that mostly said check fuses or problems related to the dimmer switch.
The dimmer switch works just fine (the overhead lights come on when the dial is fully clicked up) and all the fuses checked out except for one, the IP Dimmer fuse as listed on the removable panel from the dash. It's a 5 amp fuse, and so on my first attempt to correct this problem I put a new one in, turn on the ignition (right before crank) and turned on the lights. Still no dash lights, and the digital clock disappears, too.
So I turned everything back off (including the ignition) and pulled that fuse again, it was blown.
Anyone know what's up with this particular fuse and what's causing this? Here's a little more detail on the symptoms of the dash lights:
-ABS/Air bag lights, check engine, etc, post on during the key turn to ignition.
-Speedo, tach, and all other gagues function normally, including good readings from the voltmeter
-The clock comes on, then goes out as soon as you turn the headlight switch to Parking lights, or to headlights.
-Headlights and foglights work, with high beams.
So really I'm not quite sure where to go from here, short of sending him and the car to a dealer. Can anyone give me some advice on this particular fuse and the related problem? Thanks!!
The dimmer switch works just fine (the overhead lights come on when the dial is fully clicked up) and all the fuses checked out except for one, the IP Dimmer fuse as listed on the removable panel from the dash. It's a 5 amp fuse, and so on my first attempt to correct this problem I put a new one in, turn on the ignition (right before crank) and turned on the lights. Still no dash lights, and the digital clock disappears, too.
So I turned everything back off (including the ignition) and pulled that fuse again, it was blown.
Anyone know what's up with this particular fuse and what's causing this? Here's a little more detail on the symptoms of the dash lights:
-ABS/Air bag lights, check engine, etc, post on during the key turn to ignition.
-Speedo, tach, and all other gagues function normally, including good readings from the voltmeter
-The clock comes on, then goes out as soon as you turn the headlight switch to Parking lights, or to headlights.
-Headlights and foglights work, with high beams.
So really I'm not quite sure where to go from here, short of sending him and the car to a dealer. Can anyone give me some advice on this particular fuse and the related problem? Thanks!!
08-05-2003, 01:50 AM
#4
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Join Date: Apr 2002
Location: sebewaing, mi
Posts: 1,309
agreed with above, try grounding the radio direct to the cars body and don't use factory wiring. common mistake in hard wiring is checking the dimmer for ground, it shows ground so you use it. but when you turn the lights on it becomes a postive and blows fuses.
try regrounding it and track the wire if it still does it, you must have a short somewhere.
try regrounding it and track the wire if it still does it, you must have a short somewhere.
08-05-2003, 04:37 PM
#5
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Thank you
The radio player is still stock (the Bose system), but perhaps it's come loose (wires) over the years. I'll try that once, except if I take out his radio, won't the Theft deturrent (sp?) lock it out when I reinstal it? The car was bought used and I don't know if they ever changed the code, nor do I know if there's a universal one.
08-06-2003, 12:43 PM
#7
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Join Date: Aug 2001
Location: Northern Virginia
Posts: 15
Short to ground on the power circuit. The fuse is blowing because the short is before the load(s) which probably consists of the rheostat (dimmer switch) and probably the clock. You need two things to diagnose this sort of problem, a voltmeter and a wiring diagram. I'd start by disconnecting the fuse and the first load in the circuit (open the ground circuit) and setting the DVOM (digital volmeter) to ohms. Then connect the DVOM into the circuit side of the fuse (not the power side) and ground. If you have resistance then that verifies the short to ground and then comes the fun part, tracing along the wire for the short to ground.
If the first load in the circuit is OK, then reconnect the first load and disconnect the second load and repeat the above procedure until you've located the problem. Just a process of elimination.
Not fun and not easy and if you take it to the dealer you're going to pay for diagnostic time of $75 - $85 an hour plus repair. If you're handy with a DVOM then look at section 8A of the GM 1994 Fbody manual to find the wiring diagram, read the diagnostic section and then start tracing. Reading the diagnostic section will guide you through the trouble shooting process and will help you determine if the problem is with the wiring and/or with the loads.
If the first load in the circuit is OK, then reconnect the first load and disconnect the second load and repeat the above procedure until you've located the problem. Just a process of elimination.
Not fun and not easy and if you take it to the dealer you're going to pay for diagnostic time of $75 - $85 an hour plus repair. If you're handy with a DVOM then look at section 8A of the GM 1994 Fbody manual to find the wiring diagram, read the diagnostic section and then start tracing. Reading the diagnostic section will guide you through the trouble shooting process and will help you determine if the problem is with the wiring and/or with the loads.
Last edited by SS Aloha; 08-06-2003 at 01:05 PM.
08-06-2003, 12:53 PM
#8
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Thanks for the info.
I actually spent the morning pulling the bolster and bezel out so I could check out the wires to the dimmer switch. I do have both of the Service Manuals, and I found the page with the schematic for that switch and fuse.
Here's what I've found so far:
Brown wire into the dimmer is the power lead. The teal wire (or what the manual calls dark green :S) activates as power when the switch is moved from bottom to top. At dead bottom there's nothing (cuz there'd be no light thus no power).
That teal wire runs from the dimmer then to the #13 IP Dimmer fuse, and outputs to a grey wire. The diagram, as it seems, splits and delivers that grey wire to every operable lamp and switch in the dash and console (anything that dims).
I never checked ohms, though...
so I'll follow your recommendation and see what that shows. If I understand you right then, I'd have to start checking each recepting switch of that grey lead in the diagram to find the short to ground? Sigh...I think I'm gonna make my Dad pay ME shop rate for this. LOL
I'll see what turns up of this. Thanks again to all those who've inputed so far! This is a helluva lot better place to get answers then where I go for my Stratus @ Stratusphere.
I actually spent the morning pulling the bolster and bezel out so I could check out the wires to the dimmer switch. I do have both of the Service Manuals, and I found the page with the schematic for that switch and fuse.
Here's what I've found so far:
Brown wire into the dimmer is the power lead. The teal wire (or what the manual calls dark green :S) activates as power when the switch is moved from bottom to top. At dead bottom there's nothing (cuz there'd be no light thus no power).
That teal wire runs from the dimmer then to the #13 IP Dimmer fuse, and outputs to a grey wire. The diagram, as it seems, splits and delivers that grey wire to every operable lamp and switch in the dash and console (anything that dims).
I never checked ohms, though...
so I'll follow your recommendation and see what that shows. If I understand you right then, I'd have to start checking each recepting switch of that grey lead in the diagram to find the short to ground? Sigh...I think I'm gonna make my Dad pay ME shop rate for this. LOLI'll see what turns up of this. Thanks again to all those who've inputed so far! This is a helluva lot better place to get answers then where I go for my Stratus @ Stratusphere.
08-06-2003, 01:03 PM
#9
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Join Date: Aug 2001
Location: Northern Virginia
Posts: 15
Just remember that on a DVOM the ohms (resistance) check is made in an unpowered circuit but removing the fuse ensures that there is no power. Using the ohms setting just checks for continuity in the circuit but by disconnecting the loads and checking for continuity, you are searching for that short circuit to ground and it can be in the wiring or the load.
Yikes, every lamp in the dash!
Yikes, every lamp in the dash!
08-06-2003, 02:52 PM
#11
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Not that I'm aware of. (It's Dad's car, not mine).
I did the like Aloha suggested above. In the non-powered (outbound) side of the fuse (grey wire), it shows .07-.10 resistance. I assume that's bad judging from his post. So I followed the grey wire in the schematic of the Service Manual. I've done one item at a time, first the headlamp switch, foglight switch, defrost switch, HVAC controls, and radio. Unplugging each one of those at a time and testing still results in the same reading above. Only thing I haven't tried yet is the instrument cluster itself. Right about the time I unbolted that the battery died (realized with the headlamp switch ON, so were the headlights, duh!)
So I'm posting here while that's recharging. So I guess unless the Instrument Cluster fails, then I suppose the actually wiring from the fuse to the distribution point may have some problem.
Oh one more note...with the headlight switch completely off, there is no resistance. As soon as it goes on, it hits that reading.
I did the like Aloha suggested above. In the non-powered (outbound) side of the fuse (grey wire), it shows .07-.10 resistance. I assume that's bad judging from his post. So I followed the grey wire in the schematic of the Service Manual. I've done one item at a time, first the headlamp switch, foglight switch, defrost switch, HVAC controls, and radio. Unplugging each one of those at a time and testing still results in the same reading above. Only thing I haven't tried yet is the instrument cluster itself. Right about the time I unbolted that the battery died (realized with the headlamp switch ON, so were the headlights, duh!)
So I'm posting here while that's recharging. So I guess unless the Instrument Cluster fails, then I suppose the actually wiring from the fuse to the distribution point may have some problem.
Oh one more note...with the headlight switch completely off, there is no resistance. As soon as it goes on, it hits that reading.
08-06-2003, 02:55 PM
#12
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Originally posted by NineSevenWS6
Has there been anything removed/replaced latley?
Has there been anything removed/replaced latley?
08-06-2003, 04:32 PM
#14
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Hmm..no little lights on the switches. Maybe the Pontiac's have 'em, but this don't.
Anyway, I pulled the instrument cluster and tested that, same result. Still resistance, and the radio clock still disappears, so I'm thinking it's a wire thing now.
Anyway, I pulled the instrument cluster and tested that, same result. Still resistance, and the radio clock still disappears, so I'm thinking it's a wire thing now.