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Blown fuse questions


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30 replies to this topic

#1 fnlyfnd

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Posted 18 September 2006 - 05:20 PM

My illumination fuse blows when I have my lights on and open the glove compartment. Anyone have any ideas. I could do w/o someone saying a short somewhere. Why would the glove compartment light have a short neways

#2 gbhrps

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Posted 18 September 2006 - 05:45 PM

You've answered your own question! There is a dead short somewhere in the glove box lighting circuit. Either the bulb socket, the glove box switch or the wiring harness to it have directly shorted across to another circuit somewhere in the dash. You'll have to get under there and isolate each in turn to find the culprit. Short of that, disconnect the connectors from both the switch and the bulb socket and see what happens. Can you live without a light in the glove box? If so, just remove the bulb and forget about it. Good Luck!

#3 OB99W

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Posted 18 September 2006 - 06:32 PM

My illumination fuse blows when I have my lights on and open the glove compartment. Anyone have any ideas. I could do w/o someone saying a short somewhere. Why would the glove compartment light have a short neways

The glove compartment light is turned on when the switch completes a path to ground. The problem you describe, assuming the wiring diagram I have is accurate, can only be caused by a short in a very limited area. I suspect that the short is right across the lamp socket, since if that's the case the hot side of the lighting circuit would get grounded ("shorted out") when the switch closes.

Such a short could be as simple as the bulb itself being bad; I've seen situations where a piece of broken filament lodges in a manner which can cause that, or vibration moves the filament contact/support wires causing them to touch. So, the first thing I'd suggest is to remove the bulb, and see if the problem goes away. If it does, get a new bulb. If not, look closely at the socket and see if there's an obvious short there.

#4 fnlyfnd

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Posted 27 September 2006 - 08:07 PM

Well, its not the bulb. I tried tonigh w/o the bulb in it, and its still blew. Man this blows, I think I might just cut the wires instead of trying to fix the problem. Anyone have a wiring diagram that they can either post on the site or send me in a email?

From what I am getting from your descriptin OBW99, is a loose ground wire on the socket itself? so maybe just solder the wire in the right place? Guess I'll have to take it all apart and screw with it then.

#5 jon38iowa

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Posted 27 September 2006 - 11:14 PM

My illumination fuse blows when I have my lights on and open the glove compartment. Anyone have any ideas. I could do w/o someone saying a short somewhere. Why would the glove compartment light have a short neways

I am going to horn in on your thread because it dove tails with my predicament;
The instrument lights no longer work on my Forester (Fuses are fine) and the issue was my mistake for installing an improper light bulb. At any rate my Mechanic recomended I replace the instrument light rheostat ( it looks kind a like a 1/4' sqaure Fuse), moreover I got one from a Dealer, but I can't seem to find anything that resembles it and certainly nothing on the steering collumn as I was
told by the non Subaru mechanic.
I guess I will have to take the lower dash, but if anyone knows the precise location of this instrument light Rheostat I would be very grateful. Note I replaced the turn signal stalk and it made no difference.
John

#6 OB99W

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Posted 28 September 2006 - 04:17 AM

Well, its not the bulb. I tried tonigh w/o the bulb in it, and its still blew. Man this blows, I think I might just cut the wires instead of trying to fix the problem. Anyone have a wiring diagram that they can either post on the site or send me in a email?

Normally, the "high" side of the bulb connects to 12V via the fuse (which of course protects some other interior illumination as well), and the bulb's "low" side goes to one contact of the switch. The other contact of the switch goes to ground, and when the switch closes (glove box door is opened) it therefore connects the bulb's "low" side to ground, completing the circuit.

In your situation, when the switch closes it's apparently shorting the bulb's "high" side to ground. Since removing the bulb didn't make a difference, that pretty much leaves only a short directly across the bulb socket as the problem. The diagram I have shows the switch and socket as one assembly, so if examining it doesn't make the problem obvious, you could unplug it.


From what I am getting from your descriptin OBW99, is a loose ground wire on the socket itself? so maybe just solder the wire in the right place?

Probably not. If a grounded wire came in contact with the "low" side of the bulb, it would just turn the glove box bulb on. If that grounded wire touched the bulb's "high" side, it would blow the fuse even without opening the door. I suppose that in a very unusual situation a ground could be close to touching the high side, and opening the door flex things enough to make contact...


Guess I'll have to take it all apart and screw with it then.

Check your private messages first.

#7 fnlyfnd

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Posted 28 September 2006 - 08:21 AM

Thanks, I sent you a pm.


As far as the rheostat, sorry i cant help you. Don't even know what a rheostat is.

#8 cookie

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Posted 28 September 2006 - 11:17 AM

A rheostat is a variable resistor that allows you to add more or less power to the dash lights in this case. It is often located right under the little knob you turn.

#9 jon38iowa

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Posted 28 September 2006 - 11:33 AM

A rheostat is a variable resistor that allows you to add more or less power to the dash lights in this case. It is often located right under the little knob you turn.

Thanks Cookie:
Unfortunately though, mine is not near the turn knob; I have taken the steering collumn all apart, no Rheostat.:confused:
John

#10 OB99W

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Posted 28 September 2006 - 01:24 PM

[...]The instrument lights no longer work on my Forester (Fuses are fine) and the issue was my mistake for installing an improper light bulb. At any rate my Mechanic recomended I replace the instrument light rheostat ( it looks kind a like a 1/4' sqaure Fuse), moreover I got one from a Dealer, but I can't seem to find anything that resembles it and certainly nothing on the steering collumn as I was
told by the non Subaru mechanic.[...]

As far as I know, the "rheostat" on your '99 Forester doesn't directly control the light dimming; it connects to an "Illumination Control Module", which does the actual controlling. The control module is a more likely failure in my opinion, based on the improper bulb probably having drawn too much current.

According to the wiring diagram I have, it appears to be a unit with wires colored green/yellow, orange/white, green/red, blue, violet, and black going to it. For '98-99 Foresters, here's info on where the modules, relays, etc., are located: http://endwrench.com...cComponInfo.pdf

By the way, I assume that not just the instrument lights are out, but also several other things like the hazard switch, radio, etc aren't illuminated. Is that correct?

I'm curious as to what part you were sold. Do you have the part number of the "rheostat", and a more-detailed description of it than you've already given?

#11 cookie

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Posted 28 September 2006 - 04:33 PM

That's pretty sophisticated 99. On my BMW it is a simple rehostat. So right hand kick panel huh? No wonder it is hard to find.

#12 OB99W

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Posted 28 September 2006 - 05:27 PM

That's pretty sophisticated 99. On my BMW it is a simple rehostat.[...]

It's probably less expensive (and easier to mount) a low-power-handling variable resistance device and have it control a higher-power-handling semiconductor circuit. A real rheostat that has to dissipate enough power is bulkier and could get sufficiently warm so that it can't be mounted just anywhere.

EDIT: I just verified that some places refer to the Illumination Control Unit as a "rheostat" (I guess that's a throw-back to older times). On my own '99 Legacy OB, it's mounted to the back side of the lower dash panel (beneath the steering wheel), easily accessed by removing two screws at the lower edge and gently pulling at the top to free the clips. It's part number 83023FA000, and says "Illumi Con Unit" on it; the same unit is used on the '99 Forester, but the location is apparently different.

#13 jon38iowa

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Posted 29 September 2006 - 12:35 AM

As far as I know, the "rheostat" on your '99 Forester doesn't directly control the light dimming; it connects to an "Illumination Control Module", which does the actual controlling. The control module is a more likely failure in my opinion, based on the improper bulb probably having drawn too much current.

According to the wiring diagram I have, it appears to be a unit with wires colored green/yellow, orange/white, green/red, blue, violet, and black going to it. For '98-99 Foresters, here's info on where the modules, relays, etc., are located: http://endwrench.com...cComponInfo.pdf

By the way, I assume that not just the instrument lights are out, but also several other things like the hazard switch, radio, etc aren't illuminated. Is that correct?

I'm curious as to what part you were sold. Do you have the part number of the "rheostat", and a more-detailed description of it than you've already given?

OB99W:
Thank You for advice! Here's the story: I atempted to replace the shift lever
light bulb with one from Radio Shack, however within a few seconds of installing I smelled smoke! Quickly I removed the offender, but it was too late. I now have no dash lights, shifter light and heater/ Air control light; All the other lights work fine,radio is perfect, and the hazards work.
I took the car to my local mechanic, morever he said, "it looks like the instrument Light Rheostat," and " likely it is connected to the turn signal stalk." I would have had this fellow fix this but he said to, " go to Subaru."
To be honest I would rather replace half the dash board myself then go to my local dealer.
So far I have installed a new turn signal assembly ( the entire unit) and checked the fuses ( inside and under hood). I have now this new $81.00 Rheostat part # 83023 FA000. It is a
1-2' Inch boxed shapped device and has a connection port to one end and steel holding plate on the other.
This Satuday I guess I will be once again tackling this project; Thanks again for your response- The kicker in the saga, Subaru gave me a free bulb for the shifter.:headbang:

#14 OB99W

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Posted 29 September 2006 - 07:48 AM

OB99W: Thank You for advice!

You're welcome; let's see if we can clarify things a bit further.


[...]I now have no dash lights, shifter light and heater/ Air control light; All the other lights work fine,radio is perfect, and the hazards work.[...]

Let's make sure we're on the same page; I was only asking about the illumination of the radio dial and hazard switch "button", not whether the radio plays or the hazard lights flash.

The reason I'm asking is because 83023FA000 controls more than the "dash lights, shifter light and heater/ Air control light" that you've mentioned. If those are the only lights out, 83023FA000 may be okay, but a wire in the harness may have burned, etc.

If in addition to the lights you previously mentioned, all from the list below are out, then 83023FA000 is probably bad, so go ahead and replace it. (The End Wrench article that I previously provided a link to indicates it's located under the dash above the right kick panel on your Forester.)

1) Front Foglight Switch Illumination
2) Hazard Switch Illumination
3) Rear Defogger Switch Illumination
4) Cruise Control Main Switch Illumination
5) CD Illumination
6) Radio Illumination

If not all of the above are out, which work and which don't? Please tell me by number, keeping in mind I'm only talking about lighting of the switch button, dial, etc.

#15 jon38iowa

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Posted 29 September 2006 - 11:43 AM

You're welcome; let's see if we can clarify things a bit further.


Let's make sure we're on the same page; I was only asking about the illumination of the radio dial and hazard switch "button", not whether the radio plays or the hazard lights flash.

The reason I'm asking is because 83023FA000 controls more than the "dash lights, shifter light and heater/ Air control light" that you've mentioned. If those are the only lights out, 83023FA000 may be okay, but a wire in the harness may have burned, etc.

If in addition to the lights you previously mentioned, all from the list below are out, then 83023FA000 is probably bad, so go ahead and replace it. (The End Wrench article that I previously provided a link to indicates it's located under the dash above the right kick panel on your Forester.)

1) Front Foglight Switch Illumination
2) Hazard Switch Illumination
3) Rear Defogger Switch Illumination
4) Cruise Control Main Switch Illumination
5) CD Illumination
6) Radio Illumination

If not all of the above are out, which work and which don't? Please tell me by number, keeping in mind I'm only talking about lighting of the switch button, dial, etc.


Thank You for providing the link to endwrench, however I was unable to access it despite trying both of my browsers. Can I ask what side of " kick plate" is the rheostat on driver side or passenger?
Here's the scoop on the illumination:
1) Fog light switch lights fine.
2) The hazard button has never lit up, at least since Iv'e owned this used car.
3) Rear defogger, I will have to get back with you on.
4) Cruise control has also never lit up for me.
5) CD/ Radio works and shines brightly as before ( this is an expensive after market unit).
6)'Same as Above
I am going to replace the rheostat regardless because: I have it, is not returnable, and it eliminates yet one more possible problem.
Seperate and from the lighting issue, I will be replacing the heater control unit; This, as on mine the buttons are working a little loosely, moreover, I got a great deal (ebay)on a like new unit- $30.00! This price included ashtray, surround bezel, and power port.
John

#16 cookie

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Posted 29 September 2006 - 11:49 AM

the right kick panel is the passenger side. This is a pretty confusing place for it and may be why you have difficulty finding it. Quite an elaborate system for a simple Forester.

#17 jon38iowa

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Posted 29 September 2006 - 12:05 PM

the right kick panel is the passenger side. This is a pretty confusing place for it and may be why you have difficulty finding it. Quite an elaborate system for a simple Forester.

Simple is not a word I use for late model Subaru.LOL, I am assuming this is the right kick panel above and in front of the door; Indeed there is a lot back there. I found that out when I replaced the carpet.
Thanks Cookie
John

#18 OB99W

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Posted 29 September 2006 - 12:27 PM

Thank You for providing the link to endwrench, however I was unable to access it despite trying both of my browsers. Can I ask what side of " kick plate" is the rheostat on driver side or passenger?
Here's the scoop on the illumination:
1) Fog light switch lights fine.
2) The hazard button has never lit up, at least since Iv'e owned this used car.
3) Rear defogger, I will have to get back with you on.
4) Cruise control has also never lit up for me.
5) CD/ Radio works and shines brightly as before ( this is an expensive after market unit).
6)'Same as Above
I am going to replace the rheostat regardless because: I have it, is not returnable, and it eliminates yet one more possible problem.[...]

It's too bad you can't access End Wrench. Yes, the right side is passenger, although I must admit that location isn't as near where the circuit is used as it could be; maybe things are too tight in the Forester. Anyway, the article says it's under the dash, above the kick panel.

It could be that the bulbs are out in the switches that don't light. If the radio/CD doesn't dim when using the control, whomever installed the unit didn't tie it into the "rheostat" circuit, which would explain why it's lit when other things aren't. If the aftermarket radio/CD was installed before you got the car, it would make me wonder if the wiring was damaged and that's why certain things weren't lit since you got the car.

Best of luck; hopefully replacing the module (ummm, "rheostat" :) ) will fix at least the instrument and shifter lights.

#19 cookie

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Posted 29 September 2006 - 12:29 PM

Our current busses use 12 computers if I recall correctly. I only see the setup when I am a judge at our yearly maintence competition. When I was a mechanic we had no computers and everthing was mechanical relays.
It is quite amazing just how complicated these things are getting. We have an ECU, a tranny control unit for automatics, probably a seperate computer for the ABS system, the airbags SRS system I'm sure has a computer, and much is linked by speed signals at the least. Even the bloody speedometer is complicated.
Now I know that my dash lights are chip controlled???

#20 cookie

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Posted 29 September 2006 - 12:29 PM

Our current busses use 12 computers if I recall correctly. I only see the setup when I am a judge at our yearly maintence competition. When I was a mechanic we had no computers and everthing was mechanical relays.
It is quite amazing just how complicated these things are getting. We have an ECU, a tranny control unit for automatics, probably a seperate computer for the ABS system, the airbags SRS system I'm sure has a computer, and much is linked by speed signals at the least. Even the bloody speedometer is complicated.
Now I know that my dash lights are chip controlled???

#21 cookie

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Posted 29 September 2006 - 12:30 PM

A momentary glitch

#22 OB99W

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Posted 29 September 2006 - 12:44 PM

[...]Now I know that my dash lights are chip controlled???

Yeah, and as I'm sure you also know, there's an "igniter" between the ECU and the ignition coil (integrated into the coil pack on later models), etc. It's kind of amazing, but properly designed semiconductor-based switching circuits tend to be more reliable than the mechanical parts they replace. Of course, accidentally shorting something doesn't add to their life. :)

#23 cookie

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Posted 29 September 2006 - 01:12 PM

The only electrical bits I've replaced on my 130,000 mile Forester are a few light bulbs and the timed out oxegen sensor.
By this time on the older cars I would have been through a few alternators or generators and a bunch of points and condensors. I agree with you that the modern stuff is much better.

#24 jon38iowa

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Posted 29 September 2006 - 01:26 PM

It's too bad you can't access End Wrench. Yes, the right side is passenger, although I must admit that location isn't as near where the circuit is used as it could be; maybe things are too tight in the Forester. Anyway, the article says it's under the dash, above the kick panel.

It could be that the bulbs are out in the switches that don't light. If the radio/CD doesn't dim when using the control, whomever installed the unit didn't tie it into the "rheostat" circuit, which would explain why it's lit when other things aren't. If the aftermarket radio/CD was installed before you got the car, it would make me wonder if the wiring was damaged and that's why certain things weren't lit since you got the car.

Best of luck; hopefully replacing the module (ummm, "rheostat" :) ) will fix at least the instrument and shifter lights.

No the radio is not affected by the dimmer switch- It stays one brightness. I it installed and think this reputable technician did a good job, at least from the looks of things.
John

#25 jon38iowa

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Posted 30 September 2006 - 04:53 PM

No the radio is not affected by the dimmer switch- It stays one brightness. I it installed and think this reputable technician did a good job, at least from the looks of things.
John

Good News!
I replaced the rheostat today and the all the lights are lit up!~ It was indeed located up and behind the right side of glove box,moreover, it hides behind a stalk of two other electrical components that look very simillar to it.
Thanks again for everyones help! Now I won't have to guess at night time speed.
John




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