GMC - voltage regulator stuffed?

[Jack]

Folks as you know my rear bulbs have been blowing. Someone mentioned to me that it could be a voltage regulator problem as this would blow my bulbs and another sign of this would be the battery electrolyte level would also be reduced.

 

Would this problem blow my main headlamps too?

I have just checked the battery and it is nearly all gone :argh:

 

So, how do I fix/replace the regulator??

 

Cheers

 

Jack.

[pop larkin]

The voltage regulator is the big black box fitted to the fire wall under the bonnet. Not sure how you go about testing it, but to replace it simply buy a new one. Or get a 12v conversion with an alternator, then you won't need to worry about the volatage regulator.

[Jack]

Cheers Pop - just come in to check the thread - (24 hour interactive manual :shocked:)

 

The problem is then that the GMC is 12 volt :argh:

 

Any thoughts?

 

Cheers

 

Jack

[pop larkin]

So your already on 12v then? Do the bulbs blow the moment you turn them on or after a while? is it all your rear bulbs, stop lights too? Are your headlamps blowing aswell? Do you still have the original harness in the GMC?

 

I have made a new harness for the Chevy to include indicators, plus I added a fusebox into it as originally there were no fuses in the harness. If you are running the original harness without a fuseable link you could have a short to earth or voltage spike that would normay blow a fuse, but instead is blowing the bulbs :???.

[Joris]

Did not this problem start to occur after you 6v to 12v (sex)change?

[Jack]

Pop - no it is just the rear bulbs - the indicators, brake lights and headlamps are fine.

 

They do not blow straight away.....

 

The batterywas new last year but the level has dropped dramatically.

[R Cubed]

Ok Jack, first things first....

 

1... Is your truck 12volts now. ?

2... Does it have an alternator ?

3... Do you use the original regulator on the bulkhead ?

4... When the truck is running, ticking over and at medium revs, 1500rpm,

do you know what the voltage is at the battery,

get a voltmeter on it and check, should be no more than 14.4 volts.

 

You say it is only the rear lights which blow ? if so are you fitting 6volt bulbs instead of 12volt !!!!!!!!!

[Mark]

Earth problem

[R Cubed]

Earth problem

 

Earth problem, how does that cause the bulbs to blow !!!

might cause them to stop working, but not to blow,

it depends what the actual problem is with Jacks truck ...............

[Jack]

Ok Jack, first things first....

 

1... Is your truck 12volts now. ?

2... Does it have an alternator ?

3... Do you use the original regulator on the bulkhead ?

4... When the truck is running, ticking over and at medium revs, 1500rpm,

do you know what the voltage is at the battery,

get a voltmeter on it and check, should be no more than 14.4 volts.

 

You say it is only the rear lights which blow ? if so are you fitting 6volt bulbs instead of 12volt !!!!!!!!!

 

Hi Rich!

 

Ok here are the answers:

 

1 - 12 volts and has been for nearly two years

2 - yes

3 - no

4 - will check this week..

 

It has been running perfectly for nearly 2 years :confused::confused:

[R Cubed]

As a quick suggestion I would say the regulator for the alternator is duff, but without knowing the volts as in my previous post cant say for sure.

[Tony B]

If it is on an alternator, and the connections are clean, then can't be anything but internal. some alternators have an added gizmo for modern cars. If not connected it can cuase overcharging, but you can't connect on an old vehicle, it's to do with tach drive. What voltage are you getting at the battery wihen idiling and when reved? If its over 13.8 volts the problem is the alternator.

[Jack]

Great stuff will check it this week!

 

The alternator was brand and came with the 12 volt kit.

 

Rich - you should move to Dorset :whistle:

[R Cubed]

Great stuff will check it this week!

 

Rich - you should move to Dorset :whistle:

 

 

 

Is that an offer :wow:

 

 

Do you have big sheds in Dorset.........:idea: :idea:

[abn deuce]

wasnt there a fellow from Dorset or some such place that had two sheds ? name was Jackson I think , recall him from Monty Python ???

[Chrisg]

yep two sheds jackson

[Jack]

4... When the truck is running, ticking over and at medium revs, 1500rpm,

do you know what the voltage is at the battery,

get a voltmeter on it and check, should be no more than 14.4 volts.

 

 

 

Ok - during the brief moment the GMC was running :argh: it reached no more that 14 volts right through the rev range........

 

Any thoughts :sweat:

 

Cheers

 

Jack.

[R Cubed]

Well that sounds ok as long as it stays at no more than 14volts. The alternator should be good for many years so would not think it is that, the bulbs you are replacing, are you sure they are 12volt ? if you are fitting 6v ones then after a short period they will blow, are you sure they are blowing and its not just a dodgy connection somewhere, after you have taken them out have you tried them on a battery !!!!!!!!!!

 

As you say the other bulbs are ok leads me to think that the ones you are putting in are 6volt, but then I am not there to see :???

[Tony B]

Yeah, the alternator sounds right, bad connection or dodgy wire.

[Jack]

Ok chaps - stuck the volt meter on them tonight and one side is ready 12v and the other 11.9v so can't see a problem there.

 

Perhaps it may be the bulbs I get from Halfords..........!

[Guest catweazle (Banned Member)]

HALFORDS.Jack stop wasting everyones time.:-D:-D:-D

[Degsy]

HALFORDS.Jack stop wasting everyones time.:-D:-D:-D

 

OHHH Gawd Jack, how many times, local auto elec factor:banghead:

[Chrisg]

OHHH Gawd Jack, how many times, local auto elec factor:banghead:

 

And cheaper

[Jack]

And great - now you tell me. What sort of site is this - we are supposed to help each other :argh::argh::argh:

 

- might crash the site again out of temper. :coffee:

[Degsy]

This was a common problem on the tippers we used to operate, they were of course 24 volt but fitting heavy duty 28 volt always cured the problem. Unfortunately I don't know of any heavy duty 12/14 volt bulbs but try 2 GOOD quality bulbs, if they fail then I think that the wiring is the likeliest culprit.