New here, need HELP with '95 Impreza Dashlight Circuit!!!

[Subarmax]

Wish I could post under happier circumstances, and I've been trying to get help with this on an another site, but I'm hoping this is the place to find people that are very familiar with this vintage of Impreza. I bought the car a couple weeks ago, really sweet car minus a few problems (didn't even notice this one on the test drive...). It's a Forest Green '95 Impreza Wagon 2.2 A/T, Tan interior, 144K, needed windshield, pass side frt drive axle replaced, there was water under the spare, other little things. I've been driving/maintaining my wife's '93 Impreza Sedan (bought brand new by her Mom) for 5 years now, and I eventually fell in love with it, although the fact that it wasn't a Hatchback always drove me a little nuts. Speaking of which...

 

This car is driving me NUTS!!! I've spent hours troubleshooting the damn thing... (Yes, I have power at the fuse). Bought a replacement turn signal arm with dimmer (not the problem) so I'll return that, and my shifter bulb was out, but replacing it with a new one makes no difference.

 

The dimmer module?

 

After finally tearing into my wife's Impreza to see how a properly working system works, this is what I found. All of the dash/shifter, etc, lights have power on both sides of the bulb pigtails. This is really weird, both power, no ground.

 

When you turn up the dashlights at the switch, one of the bulb terminals dims (loses power), and I suppose becomes more and more grounded?

 

 

On my car, the '95 wagon, I have power to both sides of the bulbs, but it stays the same no matter what you do to the dimmer switch (acts exactly the same with a different turn signal arm plugged into the wiring harness), therefore no dashlights as you can't light a bulb with 12V on each side of it.

 

Is this the dimmer module no working? I suppose it could be, although the guy at the dealership told me that the part is $100 and he's never sold one, but a few turn signal arms.

 

 

I really need to get this fixed so I can drive the car and get on with other things I need to do.

 

 

Really appreciate some help here.

 

 

Thx!!!

***

[OB99W]

Welcome to the forum.

 

[...]The dimmer module?

Perhaps

 

 

After finally tearing into my wife's Impreza to see how a properly working system works, this is what I found. All of the dash/shifter, etc, lights have power on both sides of the bulb pigtails. This is really weird, both power, no ground.

That's not weird at all. Power is applied to one side of all of the lamps. If the other side isn't grounded, you'll read approximately the same voltage there, since there's minimal voltage drop across the filaments if little current is drawn by the voltmeter. (Decent modern voltmeters have a very high input resistance.) If you want to better understand this, Google "Ohm's Law".

 

 

When you turn up the dashlights at the switch, one of the bulb terminals dims (loses power), and I suppose becomes more and more grounded?

Yes, effectively.

 

 

On my car, the '95 wagon, I have power to both sides of the bulbs, but it stays the same no matter what you do to the dimmer switch (acts exactly the same with a different turn signal arm plugged into the wiring harness), therefore no dashlights as you can't light a bulb with 12V on each side of it.

 

Is this the dimmer module no working? I suppose it could be, although the guy at the dealership told me that the part is $100 and he's never sold one, but a few turn signal arms.

The dimmer modules (Subaru calls them "Illumination Control Unit", or "Illumi Con Unit") do sometimes fail, especially if someone ties into the dimmer line incorrectly, as when improperly installing an aftermarket radio. However, there can certainly be other circuit faults that can have the same effect.

 

 

I really need to get this fixed so I can drive the car and get on with other things I need to do.

 

Really appreciate some help here.

 

Thx!!!

***

You could just try replacing the module, if the cost (new or used) isn't too much of an issue. On the other hand, if you'd like help with properly diagnosing the problem, here's what you could do:

 

1) Find the Illumi Con Unit (dimmer module)

2) Connect the neg lead of your voltmeter to a good chassis ground

3) Back-probe each of the pins at the module connector, and make note of the voltage, with the stalk control turned fully up and fully down. Note the connector pin numbers, wire colors (including stripe), etc.

4) Let us know what you get in step #3

[Subarmax]

Hi, and thx for the help.

 

When i mentioned power on both sides of one of the dashlight bulb pigtails, same on both cars, except on the car I'm trying to fix, the one side doesn't lose power as you turn up the dashlights as it does on the car that works...

 

 

I meant with the bulb out, there's power (12V) to both sides of the "bulb", there's power to both sides of the pigtail, so nothing to do with a filament transfering power. One would be hard pressed to check for power with a bulb in, especially with the ultra dinky "Green" bulbs behind the heater controls...

 

 

Not to sound too smart, and I'm always relearning something (early Alzheimers?), but I'm pretty well versed in electrical repair, Ohm's Law, etc...

 

I graduated from an Automotive Technology program in 1990 (back when they actually taught starter and alternator rebuilding), followed up by another degree in Diesel/Heavy Equipment Repair. I worked in the field as a technician, for nearly 15 years before leaving the city for good and moving out to the country, where I work on a farm, and troubleshoot/diagnose electrical stuff all the time. I actually consider myself to be way above average when it comes to understanding (the first and most important step in repairing) electrical problems.

 

When I went to school back in '88, the instructors told us "If you're flush, get a Fluke meter", they were made in Everett WA back then, not China... I still have that original Fluke 23. In fact I like the so much I have three of them, as well as an extensive set of electrical troubleshooting tools, 2 Snap On test lights, lots of leads, Weller Butane powered soldering gun. I solder/heatshrink all my connections/repairs, if I can humanly help it.

 

 

So anyway, back to the car, I am leaning towards the module now, even though I don't like to get parts unless I'm 100% sure that it needs it. I can probably get it from a junk yard, and hope that it's not defective.

 

In the meantime I'll get back to the car today, after we do the snow tires on the wife's car, and other stuff.

 

Here's a post from last fall on the net where someone's Legacy was suffering from what I guess was the very same problem, the answers given weren't too bright...

 

http://rspauto.com/answers/the-dash-lights-on-my-1993-subaru-legacy-dont-work-and-i-cant-figure-out-why-what-can-be-the-causes/#comment-135564

[OB99W]

Hi, and thx for the help.

 

When i mentioned power on both sides of one of the dashlight bulb pigtails, same on both cars, except on the car I'm trying to fix, the one side doesn't lose power as you turn up the dashlights as it does on the car that works...

I got that.

 

 

I meant with the bulb out, there's power (12V) to both sides of the "bulb", there's power to both sides of the pigtail, so nothing to do with a filament transfering power. One would be hard pressed to check for power with a bulb in, especially with the ultra dinky "Green" bulbs behind the heater controls...

So you pulled out all of the illumination "bulbs"? There are quite a few of them, and doing that would be fairly time consuming. If you didn't remove all of them, since they're in parallel, even one left in place would conduct so that it would appear that there was power applied to both leads when the "low" side wasn't being pulled towards ground.

 

 

Not to sound too smart, and I'm always relearning something (early Alzheimers?), but I'm pretty well versed in electrical repair, Ohm's Law, etc...

 

I graduated from an Automotive Technology program in 1990 (back when they actually taught starter and alternator rebuilding), followed up by another degree in Diesel/Heavy Equipment Repair. I worked in the field as a technician, for nearly 15 years before leaving the city for good and moving out to the country, where I work on a farm, and troubleshoot/diagnose electrical stuff all the time. I actually consider myself to be way above average when it comes to understanding (the first and most important step in repairing) electrical problems.

I'm sorry if you found my suggestion that you read up on Ohm's Law impertinent. It was made to be helpful to someone who appeared to not be well versed about it.

 

I'm certainly not going to get into a "credentials" contest with you -- I've purposely avoided ever posting mine, and it's not because they'd look inadequate.

 

 

When I went to school back in '88, the instructors told us "If you're flush, get a Fluke meter", they were made in Everett WA back then, not China... I still have that original Fluke 23. In fact I like the so much I have three of them, as well as an extensive set of electrical troubleshooting tools, 2 Snap On test lights, lots of leads, Weller Butane powered soldering gun. I solder/heatshrink all my connections/repairs, if I can humanly help it.

It seems you're equipped to handle the job at hand.

 

 

So anyway, back to the car, I am leaning towards the module now, even though I don't like to get parts unless I'm 100% sure that it needs it. I can probably get it from a junk yard, and hope that it's not defective.

 

In the meantime I'll get back to the car today, after we do the snow tires on the wife's car, and other stuff.

You could be a lot closer to 100% certainty if you posted the result of the measurements I suggested, but it's certainly easier to try swapping out the module.

 

 

Here's a post from last fall on the net where someone's Legacy was suffering from what I guess was the very same problem, the answers given weren't too bright...

 

http://rspauto.com/answers/the-dash-lights-on-my-1993-subaru-legacy-dont-work-and-i-cant-figure-out-why-what-can-be-the-causes/#comment-135564

They were just trying to help, as I am. The difference is, I'm apparently slightly more knowledgable.

[Subarmax]

Actually, I only took out two bulbs, the center heater illumination bulb, and the shifter, which in fact had a blown filament.

 

All grounds from the dash area are very good, no resistance to other grounds under the hood.

 

I finally got to the "dimmer module", or whatever Subaru calls it. This is what I found.

 

 

Black is a Ground, and in fact the ground is very good.

 

Green is 12V

 

Yellow is 12 V, both constant with key on/headlight switch on.

 

The other three wires are Blue/Blue/Brown, none of which are doing anything regardless of what I'm doing with the dimmer on the turn signal arm.

 

Grounding the Yellow wire (with module disconnected) instantly gets you dash lights, which are all apparently AOK.

 

 

So, the module could be faulty? or... I've had the bad luck of having both my original, and other dimmer switch (which came from a low mileage '93 Legacy) be defective.

 

At any rate, I probably going to leave the interior gutted, make a jumper from the Yellow wire to ground so I have dash lights and drive it that way until I get get to town and get another module.

 

Nice to finally see some dash lights!

 

 

;-)

[OB99W]

Actually, I only took out two bulbs, the center heater illumination bulb, and the shifter, which in fact had a blown filament.

That explains why you saw 12 volts on both sides of the lamp circuit, as I mentioned above.

 

 

[...] The other three wires are Blue/Blue/Brown, none of which are doing anything regardless of what I'm doing with the dimmer on the turn signal arm.[...]

Although the wire colors you've given don't exactly match the diagram I have, it appears that those three are the ones from the dimmer control on the stalk. You could unplug the module and verify with ohmmeter that the control is functional. There should be a fixed resistance between two of the wires as the control is turned. From either of those two to the remaining one the resistance should vary as the control is turned.

 

Assuming that not "doing anything" means you measured no voltage on any of those three wires, it appears that the module is bad. However, you should probably verify that none of the three wires has an accidental connection to ground.

[Subarmax]

Ok, I'll do all that tomorrow, and sorry if I seemed huffy, a little frazzled by this Subi I suppose, working on it is a claustrophobic nightmare to me, I like working on trucks, tractors. I have a fleet of old (60's) Dodges, simple and plenty of room around everything.

 

I'd found the two wires going to the dimmer under the column a couple days ago, a Clear (odd) coated one, and Green if I remember correctly. Going across these two with the Ohmmeter would get you 0 resistance in one direction, and something like 1.825 (k?) at the other extreme.

 

I tested the other dimmer (from the Legacy), basically the same results, except the high reading was a bit lower, like 1.325.

 

 

I suppose I could test it on Laura's car, see I get the same type of readings, and possibly eliminate the turn signal mounted dimmer for good.

 

This is exactly why I bought another Impreza ;-) It's great to have two of the same vehicles, and I'm really impressed with Subarus overall... although I have to say if her car had given me fits like this all along I wouldn't have been that crazy about getting another one.

 

Fix this dashlight issue, get a new windshield put in, repair/or replace the broken power antenna and the car will be very nice.

 

Then there was the matter of the pool of water under the spare tire...

 

Any ideas there?

 

 

Thx

[OB99W]

Ok, I'll do all that tomorrow, and sorry if I seemed huffy, a little frazzled by this Subi I suppose, working on it is a claustrophobic nightmare to me, I like working on trucks, tractors. I have a fleet of old (60's) Dodges, simple and plenty of room around everything.

I like the engine compartment of my '69 Firebird.

 

 

I'd found the two wires going to the dimmer under the column a couple days ago, a Clear (odd) coated one, and Green if I remember correctly. Going across these two with the Ohmmeter would get you 0 resistance in one direction, and something like 1.825 (k?) at the other extreme.

 

I tested the other dimmer (from the Legacy), basically the same results, except the high reading was a bit lower, like 1.325.

 

I suppose I could test it on Laura's car, see I get the same type of readings, and possibly eliminate the turn signal mounted dimmer for good.

Let's clarify the connections. The dimmer on the stalk is a 3-terminal device (potentiometer). I've attached a diagram of the connector that mates with the 83023FA000 Illumination Control Unit/Module. (It's shown from the perspective of the front of the connector, so if you're back-probing with the connector plugged in, the numbering will be "flipped".) The pinout is as follows:

1 - Terminal V3 of the stalk-mounted dimmer (an end terminal)

2 - Lamp control "output" (to all dimmable lamps)

3 - Terminal V1 of the stalk-mounted dimmer (other end terminal)

4 - Terminal V2 of the stalk-mounted dimmer ("wiper" terminal)

5 - 12 volt power in

6 - Ground

 

The above should allow verification of the stalk-mounted dimmer operation. As I mentioned before, make sure there's no short to ground on any of those three leads.

 

If the above doesn't agree with your previous measurements, etc., please let us know.