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Headlight motors keep blowing fuse by Wittendorf1986
Started on: 07-20-2013 12:38 AM
Replies: 12 (797 views)
Last post by: Bloozberry on 07-21-2013 09:24 AM
Wittendorf1986
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Report this Post07-20-2013 12:38 AM Click Here to See the Profile for Wittendorf1986Click Here to Email Wittendorf1986Send a Private Message to Wittendorf1986Edit/Delete MessageReply w/QuoteDirect Link to This Post
I have a 1985 fiero se with the 4cylinder engine and auto transmission I recently had sent in the motors to be rebuilt and I got them back and hooked them up and they went up and down several times fine and then all of a sudden the fuse blew so I put in another one and moment I started to put it in it blew before it was seated in, so I tore the motors out and redid some grounds and fixed couple wires and it is still doing it but if I u plug the motors it won't blow but once I plug one in doesnt matter which it will blow so I know it is in that area I have no idea how to track down where the problem is or how to diagnose this all wires seem to be fine I thought maybe headlight switch if it has bad wire all relays are new except isolation one and I hear that one work it has to be in the wiring please help
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MCDUCK
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Report this Post07-20-2013 01:10 AM Click Here to See the Profile for MCDUCKClick Here to Email MCDUCKSend a Private Message to MCDUCKEdit/Delete MessageReply w/QuoteDirect Link to This Post
For the fuse to blow that fast, there has to be a solid short to ground. If it blows with either motor plugged in then there are two possibilities: 1) there may have been a problem with the rebuild. Possibly after a few up/downs the motor winding melted and shorted.

If you are using gen 2 lighting then 2) applies
2) Or the control module has gone bad and is shorting under load when the motors are plugged in.

If you are using gen 1 lighting then
2) Check the relays that control the motors

You can test the motors by applying power to them directly but use an inline fuse in the test wires to protect yourself in case they are shorted. Remember these are stall motors so they continue to draw current when stalled at the up or down position.

[This message has been edited by MCDUCK (edited 07-20-2013).]

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Wittendorf1986
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Report this Post07-20-2013 02:37 AM Click Here to See the Profile for Wittendorf1986Click Here to Email Wittendorf1986Send a Private Message to Wittendorf1986Edit/Delete MessageReply w/QuoteDirect Link to This Post
When I was messing with them there is a few times I get them to work after the first few times it blew and they would work then blow fuse again then it would start over and start blowing fuses again moment I put one in. I hear the relays click all three and I replaced them very recently so I know the motors still work and they went up very good and down also, what kind of testers do I need to test everything, and how do I test the wiring and all that
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cebix
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Report this Post07-20-2013 08:19 AM Click Here to See the Profile for cebixSend a Private Message to cebixEdit/Delete MessageReply w/QuoteDirect Link to This Post
What fuse are you actually blowing? As far as I know there are no fuses to the gen1 motors, only fusible links and circuit breakers.
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Wittendorf1986
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Report this Post07-20-2013 09:32 AM Click Here to See the Profile for Wittendorf1986Click Here to Email Wittendorf1986Send a Private Message to Wittendorf1986Edit/Delete MessageReply w/QuoteDirect Link to This Post
It doesn't say on the fuse box letters wore off on where fuses off where fuse box is but when I installed my headlight motors back In I raised and lowered them several times and then I heard a pop and they stopped moving and I looked at all the fuses and found the one that blew I tried putting in another and it blew after I fixed some ground and some loose wires it didn't make a difference I managed to get them raise few more times or so and It do same thing again
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Bloozberry
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Report this Post07-20-2013 01:58 PM Click Here to See the Profile for BloozberrySend a Private Message to BloozberryEdit/Delete MessageReply w/QuoteDirect Link to This Post
Here's a picture of the fuse panel... which one keeps blowing?

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Wittendorf1986
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Report this Post07-21-2013 02:41 AM Click Here to See the Profile for Wittendorf1986Click Here to Email Wittendorf1986Send a Private Message to Wittendorf1986Edit/Delete MessageReply w/QuoteDirect Link to This Post
It is the taillight one which I wouldn't understand would blow and stop the motors from working
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Bloozberry
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Report this Post07-21-2013 07:19 AM Click Here to See the Profile for BloozberrySend a Private Message to BloozberryEdit/Delete MessageReply w/QuoteDirect Link to This Post
The tail light fuse is used to as the main motor power source to close the headlight doors only. Here's the schematic:



If you need help troubleshooting from here, just ask, but I would suspect that one of the motors is binding on the way down and is overloading the circuit. I would start by isolating each motor electrically (unplugging the dark blue wire one at a time) to see if one headlight pod works properly and the other blows the fuse. If you can isolate the problem to one side, then that's half the battle.

Edit: cleaned up schematic

[This message has been edited by Bloozberry (edited 07-21-2013).]

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cebix
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Report this Post07-21-2013 07:26 AM Click Here to See the Profile for cebixSend a Private Message to cebixEdit/Delete MessageReply w/QuoteDirect Link to This Post
The tail light fuse only powers the relays (both motor relays plus the isolation relay) but it also powers all the parking lights. Check if any wires are being caught by the headlight assemblies.

EDIT: Bloozberry: No, the tail light fuse doesn't power the circuit. You're schematic is a little worn and you can't see the part of the relay that is grounded when the motors go down (GRN).

EDIT2: Or maybe actually it does... I'm confused. My motors together draw about 30 amps when shutting down (when shorted) and my limit switches are shot so a 20 amp fuse would blow but it doesn't.

EDIT3: Yeah it really powers the circuit... weird.

[This message has been edited by cebix (edited 07-21-2013).]

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Bloozberry
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Report this Post07-21-2013 08:32 AM Click Here to See the Profile for BloozberrySend a Private Message to BloozberryEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by cebix:
The tail light fuse only powers the relays (both motor relays plus the isolation relay)


It is a confusing circuit but if you look a little more closely, when the light switch is moved anywhere other than OFF, the Tail Light Fuse is disconnected from the headlight circuit so it can not power the any of the headlight relays.

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Wittendorf1986
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Report this Post07-21-2013 08:37 AM Click Here to See the Profile for Wittendorf1986Click Here to Email Wittendorf1986Send a Private Message to Wittendorf1986Edit/Delete MessageReply w/QuoteDirect Link to This Post
The first time it blew it the headlights were up
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Wittendorf1986
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Report this Post07-21-2013 08:42 AM Click Here to See the Profile for Wittendorf1986Click Here to Email Wittendorf1986Send a Private Message to Wittendorf1986Edit/Delete MessageReply w/QuoteDirect Link to This Post

Wittendorf1986

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Member since Jul 2013
It blows on either motor left or right regardless of which on is unplugged only time it don't blow is when I unplug both motors
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Bloozberry
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Report this Post07-21-2013 09:24 AM Click Here to See the Profile for BloozberrySend a Private Message to BloozberryEdit/Delete MessageReply w/QuoteDirect Link to This Post
If it only doesn't blow when both motors are unplugged, then you can be certain that the short circuit is in the wiring for the headlight motors in the "down pods" mode. If you have a multimeter (even a cheap one) your best bet at this point will be to see if any of the following wires give zero ohms when one meter lead is placed on any end of each wire listed below and the other meter lead is placed on a known good ground:

a. isolation relay white wire;
b. isolation relay dk blue wire; and
c. isolation relay dk blue/wht wire;

For the test, pull out the Tail Fuse and unplug the wires from the isolation relay and use the exposed wire ends in the connector as your test points. The wire that gives zero ohms (as opposed to infinite ohms) is your troublesome wire. If that's not it, then post your results and we'll take it from there.
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