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Headlights go down, but not up. by Heretic
Started on: 05-14-2020 02:49 PM
Replies: 4 (116 views)
Last post by: Dennis LaGrua on 05-19-2020 12:28 PM
Heretic
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Report this Post05-14-2020 02:49 PM Click Here to See the Profile for HereticSend a Private Message to HereticEdit/Delete MessageReply w/QuoteDirect Link to This Post
I had the issue on my 86 GT where my headlights stopped going up and down all together. Lights would come on, but the motors wouldn't even try to spin. When I manually cranked them up, they wouldnt go back down when turning the switch off.

I replaced the switch with no luck. After doing some reading it seemed the isolation relay was the culprit. I swapped out the isolation relay this morning and they still wont come up, but both lights will now go down after I manually crank them up and turn the switch off.

If the relays on the headlights themselves were bad, would the lights still go down? Even if that was the case, what are the chances both would go at the same time?
Where should I be looking now?

Thanks

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Report this Post05-15-2020 03:01 PM Click Here to See the Profile for FXClick Here to Email FXSend a Private Message to FXEdit/Delete MessageReply w/QuoteDirect Link to This Post
Possibly, most auto parts stores stock the individual relays, as they are used in several different cars...Try those, Then I would suggest the motors be rebuilt. I've done a few, it's not that hard. Rodney has the kits...Then you know what ya got, and the system will be dependable, and last a long time. If the motors are the originals, they're about due anyway...
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Dennis LaGrua
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Report this Post05-16-2020 09:49 PM Click Here to See the Profile for Dennis LaGruaClick Here to Email Dennis LaGruaSend a Private Message to Dennis LaGruaEdit/Delete MessageReply w/QuoteDirect Link to This Post
It is rare that both motor relays would burn out at the same time. If both do not go up its usually the headlight switch or isolation relay. You say you replaced them but no change. Are you sure that isolation relay was good???? If so I'll take a long short guess and say that its the motors themselves.
Some detailed repair info from engineer and long time Fiero owner Oliver Scholz here:
Gen 1 Headlight motor repair guide
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" THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

[This message has been edited by Dennis LaGrua (edited 05-16-2020).]

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Heretic
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Report this Post05-17-2020 09:37 PM Click Here to See the Profile for HereticSend a Private Message to HereticEdit/Delete MessageReply w/QuoteDirect Link to This Post
I’m not 100% sure the “new” isolation relay is good, just got it off of somebody on the Facebook group. I got too excited when I plugged it in and both lights went down, then flicked the switch and was so deflated when they didn’t come back up haha.

I’ll probably order the rebuild kits from Rodney and do both motors and see how that goes.

[This message has been edited by Heretic (edited 05-17-2020).]

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Dennis LaGrua
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Report this Post05-19-2020 12:28 PM Click Here to See the Profile for Dennis LaGruaClick Here to Email Dennis LaGruaSend a Private Message to Dennis LaGruaEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Heretic:

I’m not 100% sure the “new” isolation relay is good, just got it off of somebody on the Facebook group. I got too excited when I plugged it in and both lights went down, then flicked the switch and was so deflated when they didn’t come back up haha.

I’ll probably order the rebuild kits from Rodney and do both motors and see how that goes.



The isolation relay can be tested and even bypassed. Oliver Scholtz outlines the test in the link provided. If both motors behave the same way that would be the first place to look. There could be something wrong with the motors but it would be strange but not impossible for both to fail. The motors are quite old , usually very re-buildable but you need to pay close attention to detail to take them apart and re-assemble them correctly. For instance if the motor stator assembly is replaced backwards (very easy to do) the motors will operate in reverse order. If the motor brushes are worn down, Rodney' s brush replacement kit works like a charm.

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" THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

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