GT Blowing Bulbs

[Connor 1]

Hi everyone,

 

I wonder if anyone can help. My GT has started blowing its main beam bulbs, and I'm struggling to work out what is the issue.

 

It starts with the low beam circuit in the bulb blowing, with both bulbs going at the same time, likewise the same happens eventually when on high beam. I measured the output from the connector referencing ground and was getting 15v across both high and low beams. I assume this is too high? After this happened the first time that the spotlights stayed on constantly - even without turning the lights on. I changed the main beam relay after this since it was a cheap option, but it was really just a guess. I've also found recently that the interior blower speed now varies a lot, likewise the illumination level on the dashboard.

 

I've seen mention that the earthing to the body should be checked, however I'm not sure exactly where this is?

 

Any help would greatly be appreciated!

 

Thanks a lot,

 

Connor

 

 

[DamirGTI 342]

Bad alternator voltage regulator making system overcharge .. will need to replace it , complete regulator not just the brushes as the electronics sealed inside the regulator goes bad .

 

 

D

[Connor 1]

15 minutes ago, DamirGTI said:

Bad alternator voltage regulator making system overcharge .. will need to replace it , complete regulator not just the brushes as the electronics sealed inside the regulator goes bad .

 

 

D

Thanks! I'll give that a try, I assume it sits on the alternator?

[DamirGTI 342]

Correct , it's external regulator bolted on the alternator :

 

 

.. where the yellow spade terminal plugs in .

 

On Paris Rhone/Valeo it's square box shaped , on Bosch alternators it's kinda trapeze with an round blob on top .

 

Only two torx bolts holding it on , it can be replaced on the spot no need to remove the alternator out to do so .

 

 

D

Edited January 18, 2021 by DamirGTI

[Thijs_Rallye 87 4 Cars]

Personally I'd check the engine ground strap first, if that has rotten the alternator regulator also doesn't "know" what to do.

[Connor 1]

9 hours ago, Thijs_Rallye said:

Personally I'd check the engine ground strap first, if that has rotten the alternator regulator also doesn't "know" what to do. 

Thanks! Where about can I find this? I've been struggling a bit to work out exactly where everything is since I don't have any access to it during the daylight at the moment.

[Thijs_Rallye 87 4 Cars]

Sorry, I have no idea on the GT. Follow them from the battery terminal.

[Gohn 68]

try Damir's advice with the voltage regulator and also its good to keep all the earth points in your engine bay good

 

what you're looking for is nice clean metal to metal contact, no corrosion on either the metal or wiring which inhibits current flow

the four engine bay earth points to check are :

the two main earth clusters at the front, one behind each headlight bolted to the chassis. each one has a cluster of smaller earth wires inside a splash bag

and then also check the two earth line connections that come off the Negative battery terminal. (They join together at the Neg terminal and are usually one main Brown earth cable and a thinner Green/Yellow cable) Not sure where the GT will earth its main Brown battery strap but just follow it from the Neg terminal . It will likely bolt to the top of the gearbox bellhousing just below/nearby to the battery tray. And the thinner Green/Yellow earth cable will run and bolt to the chassis behind the window washer water container to the left of the Battery

 

I've never been comfortable with electrics so try to keep the basics in good shape to avoid issues I cant fix. when the earth's are all good, the current is able to get to ground easily, completing good circuits, but when it cant earth properly due to corrosion or loose bolts etc the current will try and earth somewhere else, overloading the electrical system and blowing stuff, or just not working

 

[DamirGTI 342]

Actually , i had that once or twice ... wasn't blowing out bulbs at the time as it just started to "misbehave" , but the entire lighting on the exterior/interior where flashing like a disco fever night club !

And the charge at the battery was in excess of 15V .

 

Was old OE "Motorola" voltage regulator gone bad .. i have a few of them Motorola regs. which manifested the same life end , brushes still good but something went inside the sealed part .

 

 

D

[Connor 1]

On 1/21/2021 at 2:06 AM, Gohn said:

try Damir's advice with the voltage regulator and also its good to keep all the earth points in your engine bay good

 

what you're looking for is nice clean metal to metal contact, no corrosion on either the metal or wiring which inhibits current flow

the four engine bay earth points to check are :

the two main earth clusters at the front, one behind each headlight bolted to the chassis. each one has a cluster of smaller earth wires inside a splash bag

and then also check the two earth line connections that come off the Negative battery terminal. (They join together at the Neg terminal and are usually one main Brown earth cable and a thinner Green/Yellow cable) Not sure where the GT will earth its main Brown battery strap but just follow it from the Neg terminal . It will likely bolt to the top of the gearbox bellhousing just below/nearby to the battery tray. And the thinner Green/Yellow earth cable will run and bolt to the chassis behind the window washer water container to the left of the Battery

 

I've never been comfortable with electrics so try to keep the basics in good shape to avoid issues I cant fix. when the earth's are all good, the current is able to get to ground easily, completing good circuits, but when it cant earth properly due to corrosion or loose bolts etc the current will try and earth somewhere else, overloading the electrical system and blowing stuff, or just not working

 

Thanks for the suggestions! Started taking a look over these today and they didn't seem horrific but tried to clean them up a bit. The whole engine bay definitely needs a massive clean once the weather is better! I feel like this car is punishing me for ignoring it for a couple of months!

On 1/22/2021 at 1:09 PM, DamirGTI said:

Actually , i had that once or twice ... wasn't blowing out bulbs at the time as it just started to "misbehave" , but the entire lighting on the exterior/interior where flashing like a disco fever night club !

And the charge at the battery was in excess of 15V .

 

Was old OE "Motorola" voltage regulator gone bad .. i have a few of them Motorola regs. which manifested the same life end , brushes still good but something went inside the sealed part .

 

 

D

Managed to order up a new one, hopeful that this is the fix. Both of the brushes were worn way down, one much more than the other which I thought was interesting? I broke one of the connectors taking it off too so that will need sorted! Fun and games.

 

 

[Connor 1]

Just as a bit of an update to this. After waiting three weeks for the voltage regulator to clear customs in Germany, I finally fitted it today. I'm now 13.6 volts at the bulbs? Seems to be steady though so it does seem better. The car also starts and drives a lot sweet than before. Is that extra 1.6v enough to blow the bulbs do you all reckon?

 

 

On 1/18/2021 at 9:03 PM, DamirGTI said:

Correct , it's external regulator bolted on the alternator :

 

 

.. where the yellow spade terminal plugs in .

 

On Paris Rhone/Valeo it's square box shaped , on Bosch alternators it's kinda trapeze with an round blob on top .

 

Only two torx bolts holding it on , it can be replaced on the spot no need to remove the alternator out to do so .

 

 

D

Thanks a lot for your help on this everyone!

C