These are "Generation 2" headlights. They've always worked perfectly when out of the blue they suddenly stopped working a few days ago. The left headlight will come up while the right stays down, but neither will come down (after I manually raise the right headlight).

All fuses are ok, the dashboard lights are lit. Haven't checked the light switch yet.

Any ideas?

since it all happened at once, I would guess the controller board failed

ditto Pyrthian. If not the switch (easier to check), check the module, located inside the left front fender behind the sidemarker lamp. The service manual (if you have it) has a method to check the module.

I'll agree also. You can use my post to check it out. Pull the left inner fender and look up in front of the wheel and you will see it.

Either the open or closed signal wire will have power on it all the time. IE the open (yellow) will have power when the switch is on and the close (white) will have power on it when the switch is off. If the wires both have power when the switch is set accordingly then your module is most likely toast. Also make sure there is 12V on both the red wires. They are protected by fuseable links.
You could also test the motors by applying power directly to them to make sure they are ok. Might even be worth unplugging and replugging the connectors on the module and motors and see if it makes any difference. If you open the module (it's easy to get open) you could even take the cover off the relay and clean the contacts and see if that brings it back to life. It's a quad pole double throw relay and a pair of contacts are used in each mode so just a couple contacts having a probem could make it not work. FYI the relay is what switches to control the direction of the lights. The rest of the board is for contolling current limit and timout.

https://www.fiero.nl/forum/Forum2/HTML/087182.html

Also it seems that you have to get the correct module for the type of motors you have. Someone that was doing a swap in their car using my post had motors from one model car (think it was a Fiero or Firebird and a module from a Corvette and they would not work. The Corvette module tested OK in a vet but would not work in the Fiero. He got a Fiero module and it worked fine.
Just something to be aware of..


Here is one version of the module. I have seen three different versions so far.

[This message has been edited by Dodgerunner (edited 10-17-2008).]

It's the headlight control module. I took it out of the car and it's definitely broken (one of the MOSFETs burned up).

They are sold here in the Netherlands for (get this) almost $500 !!!!!

Unbelievable. I opened it up and there are perhaps for $10 worth of electronics inside...

surely someone can come up with a "gift" to mail you.

Cliff,
I don't know if it will work on the '88s, but I bypassed the main relay (which the control box replaces on the '88s) on an '86 & hooked up the headlight motors to the defroster switch (still running through the 2 secondary headlight relays). I like it better that way: you can put the lights up or down any time you want, & turn them off without putting them down if you like.
I posted a thread here if you want to check the wiring (but like I said it's an '86).
~ Paul
aka "Tha Driver"

I'm not a complete idiot, some parts are missing.

I got one Cliff, PM sent
Sparx22

I replaced the MOSFETs and now both headlights are working perfectly again.

I had found three places here in the Netherlands that sold the Headlight Control Module: GM offered them for $500 new. A Corvette parts dealer had them for $425 new. Some junk yards offered them for $260 used.

I ended up paying $2 in parts and 10 minutes in labor.

For future reference, I used two IRF540N MOSFETs and so far that's working perfectly.

Did you take any pictures, would like to see what you board looked like and what you replaced...

Yeah I would like to see this in a picuture myself, mosfets are voltage regulators right?
spaxrx22

No they are more like a transistor.. The FET part means "field effect transistor"
They switch faster, have less heat gain due to lower resistance of the junctions etc... .

quote Originally posted by Dodgerunner: Did you take any pictures, would like to see what you board looked like and what you replaced...

Has anyone looked at the possibility of using parts from the Firebird which used the same headlight motors starting in 1982? In those cars when the headlights went up but failed to go down it was usually caused by a main relay not much different than the individual relays found on each motor. I didn't know until this thread that any such thing as what's posted existed in the Fiero in relation to the headlight motors.

Cliff thanks for the image, it really toasted huh!

quote Originally posted by Joseph Upson: Has anyone looked at the possibility of using parts from the Firebird which used the same headlight motors starting in 1982? In those cars when the headlights went up but failed to go down it was usually caused by a main relay not much different than the individual relays found on each motor. I didn't know until this thread that any such thing as what's posted existed in the Fiero in relation to the headlight motors.

Yes I followed Dodgrunner's excellent thread on this subject and convereted to Firebird motors and a vette module. You need to do a little rewiring but well worth the effort.
Eliminating 3 relays and the internal motor limit switch makes the system less complicated and apt to fail imo. My cost was about $90.00.
sparx22

[This message has been edited by sparx22 (edited 10-26-2008).]

At least it was easy to see what failed... I'm surprised the solder fuses running from the FETs didn't blow.

Where you able to cross the parts to a MOSFET or just decided to use them?

[This message has been edited by Dodgerunner (edited 10-26-2008).]

Well, a few days ago, the headlights wouldn't go down anymore. I'm not sure this is related to the Control Module since I took it apart again and checked everything. Even resoldered all components. Maybe the wiring harness has a few broken wires since my fan sometimes stops too (I then have to "wiggle" the harness to get it to work again).

Fortunately I had bought a "new" headlight module on eBay as a spare. This one was for a Corvette but according to its part number (16523917) it should work in a Fiero just fine. But it didn't. When I put this module in my car, the headlights won't go up or down...

Everywhere I checked (like GMPartsDirect.com and here) it says it should work in a Fiero. Can anyone confirm this? Does anyone actually use a Headlight Control Module with part number 16523917?

I believe (who was that?) ran into this same thing when he was doing a gen1 to gen2 conversion using my headlight post.

He had a couple Vet modules that worked in his vet but would not work in the Fiero. He got a Fiero module and it worked fine.

Apparently the modules and motors are somewhat match and if the current is off to far they don't work.

He could provide more info as far a module #s.

[This message has been edited by Dodgerunner (edited 11-07-2008).]

Cool, thanks.

Maybe that was me, my lights went only one way, forget which way now, but if I reversed the polarity then they reversed but still only traveled in one direction. It was the wrong modules ( I had two) that caused this.

I have a module stated from an 84 or 86 Vette #16521291 in my car working with 1986 firebird motors, 2nd gen fiero type. WIred as Dodgerunner mapped out.

I had a GM 16525685 and it did not work as I mentioned above. It did not work in my C5 vette either. It was for these: WORKS WITH: 90-02 FIREBIRDS ,90-92 BUICK REATTA , 90-92 OLDS TORONADO and 90-94 PONTIAC SUNBIRD


LON at Top-Down Solutions has a handle on the modules that do work with the Fiero. I got my 2nd module from him which now sits on the shelf.
Top Down is on the web and Lon is a very helpful guy with this stuff. He is in a Firebird collector club so he understands our situation when trying to sort things like this out.

sparx22

[This message has been edited by sparx22 (edited 11-08-2008).]

i have found that i have an 87-88 module in my box of parts.
it's yours if you want it.

quote Originally posted by buddycraigg: i have found that i have an 87-88 module in my box of parts. it's yours if you want it.

Great, thanks! I'm first going to make sure the one I got is actually defective. If it is, I'll let you know. I'll need your PayPal then since I don't like taking stuff for free.

OK. First: big sigh.

Let's go back to the original problem. The right headlight wouldn't go up or down. The left headlight would only go up. What I can remember is that sometimes the left headlight would go down intermittently, meaning I would set the switch to off and it sometimes would go down just a little bit, sometimes all the way. But most of the time nothing happened and the headlight would stay up.

So I removed the module, opened it up and found the burned Mosfet. I also found a trace on the circuit board that was cracked. I replaced the Mosfets and resoldered the trace. When I hooked up the module again, I also replaced the headlight switch since I had bought a new one. Now the headlights worked perfectly again. Both went up and down. But after the first trip with the headlights up, they wouldn't go down again. I removed the module and replaced it with a new one from a Corvette which supposedly should work too. It didn't. Headlights wouldn't go up or down. So I opened up the old module, resoldered everything and tested it. Still the same problem. Headlights went up but not down. Just for the heck of it, I tried fiddling with the new headlight switch. And lo and behold, if I pressed down on the "Off" position really hard, the headlights went down. I opened up the new switch and saw that one of the switches wasn't working properly. I repaired it and now the headlights are working perfectly again.

The moral of the story: if you are repairing something, only replace one part at a time.

Wow and I thought things like this only happened to me!!!!!!!!!!!!!!!!!!!!!

Glad you got it Cliff.

jim

[This message has been edited by sparx22 (edited 11-11-2008).]

Hey great you got the module fixed. What MosFet did you cross them to for the replacement?

Random fiddling comes to the rescue again! That's a proven technique, btw.

JazzMan

quote Originally posted by Cliff Pennock: Just for the heck of it, I tried fiddling with the new headlight switch. And lo and behold, if I pressed down on the "Off" position really hard, the headlights went down. I opened up the new switch and saw that one of the switches wasn't working properly.

I had a headlight switch like that in one of my first Fieros and I actually prefer the switch to work in that manner. So much so that I swapped this switch over to the last GT that I bought.

I like having the ability to turn the lights off without needing to flip them down, especially if I know I'll be using the lights again in a few minutes. Less wear and tear...

I was bored....

Cliff's OE MOSFET part # PA75N85S is obsolete but it did have some newer # to use...
Equivalences: BUZ 24, 2N6763, 2SK561, 2SK906, 2SK1429

Dodgerunner's MOSFET part # BUZ10S2 is a Siemens #
Datasheet

Mouser "said" NTE2389 will work for BUZ10S2. Cost $7.20

So we have more part # to use...

------------------
Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave (It's also at the top and bottom of every forum page...)

So will that corvette module work with your new headlight switch? I'm just trying to find out if the corvette modules won't work at all.

Holy old thread resurrection, Batman!

My headlight module is fried again. This time beyond repair because not only did the MosFet burn itself up, the relais as well.





What I'm wondering is, what is causing this? When I tried to raise the headlights by hand, I noticed a distinct difference between the left and right headlight motor. It was very easy to turn the headlight motor knob of the right headlight, but it was much harder to turn the knob of the left headlight.

So is the left headlight motor fried too?

You may want to take apart the headlight motor and check to make sure something isn't binding.

I wonder if your brushes in the motors are shot and the bush lead is shorting out on something.

Wow, that really took a hard hit...

I might be able to repair it after all. The MOSFET is easily replaced and I can use the relay from the non working Corvette module. The two relays are exactly the same with only one difference: the relay in the Fiero module has a 12V coil while the relay from the Corvette module has a 9V coil. Would that be a problem?

Afternoon Cliff -- Your safety is the top priority of all of us in the fiero community. Until you get the lights repaired I suggest you take the train.

quote Originally posted by steve308: Until you get the lights repaired I suggest you take the train.

Relay is available worldwide too.

See cave, link in Gen 2 HL motor.

Bad motor fried module? Maybe.
Bad module fried 1/both motors? Likely.

Very likely have other components failed besides MOSFET and relay. "Load sensor" is one area. You fix MOSFET and relay but module can't read motor load then module will fry motor(s) again...
I would get a new/used module and maybe fix motors.

------------------
Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave (It's also at the top and bottom of every forum page...)

Hi Cliff, I think I have an extra module in my parts bin in the shop. I'll check on Monday and if so I'll send it to you.

Looks like you may want to increase the size of those mosfet heatsinks. Why the hell would they put such small heatsinks on such a high amperage part?


Edit to add......I just realized YOU added the heatsinks. They still didn't help with the burn up.

[This message has been edited by IMSA GT (edited 05-08-2011).]

quote Originally posted by IMSA GT: Looks like you may want to increase the size of those mosfet heatsinks. Why the hell would they put such small heatsinks on such a high amperage part? Edit to add......I just realized YOU added the heatsinks. They still didn't help with the burn up.

Yep, I added those heatsinks because I couldn't believe either there were none.

On the other hand, maybe they are supposed to have no heatsinks so they'll burn up faster thus protecting the motors.