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Faulty alternator or charge relay?

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Faulty alternator or charge relay?

Postby Marty » Tue May 15, 2012 5:18 pm

G'day, my dash lights (fuel, cooling, brakes) all came on this morning on the way to work as it seems is typical of a charging issue . I am wondering if this is caused by a faulty alternator or charge relay. The volts guage on the dash is showing the alternator to be working fine, a bit over 12 volts and increasing up to 14 as the engine rpm increases. Most people who have this symptom seem to find that the volts are off the guage which has me confused. I don't want to change the alternator to find it's only a relay. Any help appreciated. Cheers, Marty.
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Re: Faulty alternator or charge relay?

Postby geeves » Tue May 15, 2012 5:29 pm

Thats a little different to most peoples observation. Most times the volts stick at 12 and the battery goes flat. My money is still on the charge relay though.
if the brushes or diode pack die on the alternator the lights stay on and volts = 12 till battery goes flat.
If the regulator fails it goes high volts until stator winding burns out This brings the lights on but the charge relay is damaged at the same time and will stick causeing the lights to go out but volts at this point = 12 so despite no warning battery still goes flat.
Sanding your knuckles before starting work can help. That way you cant skin them
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Re: Faulty alternator or charge relay?

Postby Marty » Tue May 15, 2012 6:55 pm

I just put the multimeter across the battery and it's measuring 14v at idle so all seems to be good with the charging. Still can't work out why the lights are on??? Maybe something unrelated? Anyone got a wiring diagram showing the circuit these guages are on?
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Re: Faulty alternator or charge relay?

Postby BlairNZ » Tue Aug 14, 2012 3:30 pm

I appear to be having the same issue with my 3.1 Pighorn - so the charge relay is the blue one located in the fusebox under the bonnet? I have travelled down to my parents place so am away from my shed and parts so I am hoping it is a quick, simple fix so I can get home again without issue!
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Re: Faulty alternator or charge relay?

Postby geeves » Tue Aug 14, 2012 7:21 pm

2 possible relays. Either blue or brown. If its blue borrow one from your other truck It will be the same
Sanding your knuckles before starting work can help. That way you cant skin them
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Re: Faulty alternator or charge relay?

Postby BlairNZ » Tue Aug 14, 2012 8:17 pm

Cool, I know there is a blue one under the bonnet, but since I am down in Levin and all my other trucks are in Napier, I am hoping to find a friendly wrecker around the region somewhere who will let me try before I buy... Hahaha All else fails, I will just have to hold on until I get back to Napier because everything else seems to be working except for the A/C!
"If at first you don't succeed, find a bigger hammer"
"If you can't fix it with a hammer, you have electrical problems"
"Hammers fix EVERYTHING"
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Re: Faulty alternator or charge relay?

Postby BlairNZ » Wed Aug 15, 2012 10:39 am

It was this lil bugger... thanks for the ideas etc, saved a lot of frustration!
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"If at first you don't succeed, find a bigger hammer"
"If you can't fix it with a hammer, you have electrical problems"
"Hammers fix EVERYTHING"
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1993 Isuzu Bighorn SWB - 3.1TDi auto
1993 Isuzu Mu - 2.8TD converted to manual (river truck)
1995 Isuzu Mu - 3.1TD 5spd (river truck)

Re: Faulty alternator or charge relay?

Postby michaelmotes » Sun Sep 23, 2012 4:47 am

I'm having a similar problem. It started yesterday. The day before the battery was dead when I went out to start it that morning. The battery was dated 2003, so I thought that it was just old and replaced it. Everything seemed fine until driving home yesterday. At some point, the volts dropped to 12 while at idle, and the trac, battery, and brake lights came on. Then after giving it some gas, the volts bounced back up to 14, and the lights went out. This happened again at the next red light. Now, the volts won't move from 12, and those dash lights stay on until i rev it to about 2500 rpms. Even at 2500 rmps the volts stay at 12.

Any advice would be much appreciated. It's a 1997 Trooper, US model.
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Re: Faulty alternator or charge relay?

Postby michaelmotes » Sun Sep 23, 2012 4:48 am

BlairNZ wrote:It was this lil bugger... thanks for the ideas etc, saved a lot of frustration!

What did the blue relay control? I don't have a blue one in mine. Thanks.
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Re: Faulty alternator or charge relay?

Postby geeves » Sun Sep 23, 2012 7:16 am

is yours a petrol model? whioch engine? They have a different settup
Sanding your knuckles before starting work can help. That way you cant skin them
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Re: Faulty alternator or charge relay?

Postby michaelmotes » Sun Sep 23, 2012 7:32 am

geeves wrote:is yours a petrol model? whioch engine? They have a different settup

Yes, the petrol model. 3.2L V6 engine
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Re: Faulty alternator or charge relay?

Postby geeves » Sun Sep 23, 2012 5:08 pm

bad alternator
either brushes or diode pack
Sanding your knuckles before starting work can help. That way you cant skin them
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Re: Faulty alternator or charge relay?

Postby michaelmotes » Mon Sep 24, 2012 2:53 am

Thanks for the replies.

When I tightened up the fan/alternator belt, the problem revealed itself. Maybe the pulley was loose or slipped enough to loosen the belt, and then when I tightened the belt, the pulley just gave out.

I replaced the pulley bracket, and everything seems ok.

Image

I just bought this Trooper with 180k miles, so I'm probably going to have to turn a wrench or two every now and then. :D
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Re: Faulty alternator or charge relay?

Postby geeves » Mon Sep 24, 2012 5:48 pm

thats a different view of an engine. The other belts dont look to good either.
3.2 v6 in 87 trooper? the 3.2 isuzu engine was released in 92 The chevy engine was 3.1 and was used in some USA Troopers. What are the first 6 characters of the chassi number from the firewall plate (UBSxxx) and does it have any of these option codes? LL2, LW3,RJQ,RLJ,RLU,or RLV ?
Sanding your knuckles before starting work can help. That way you cant skin them
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Re: Faulty alternator or charge relay?

Postby michaelmotes » Tue Sep 25, 2012 1:39 am

geeves wrote:thats a different view of an engine. The other belts dont look to good either.
3.2 v6 in 87 trooper? the 3.2 isuzu engine was released in 92 The chevy engine was 3.1 and was used in some USA Troopers. What are the first 6 characters of the chassi number from the firewall plate (UBSxxx) and does it have any of these option codes? LL2, LW3,RJQ,RLJ,RLU,or RLV ?

It is a 1997 Trooper. The AC belt is a little beat up but still working. :) It seems like the last owner or mechanic who installed the ac cut off a rib or two.
Last edited by michaelmotes on Tue Sep 25, 2012 1:50 am, edited 1 time in total.
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Re: Faulty alternator or charge relay?

Postby michaelmotes » Tue Sep 25, 2012 1:43 am

So I had the same voltage problem on the way in to work today. After about 30 minutes of driving, the volts dropped from 14 to just below 12. Then the battery, brake, and trac lights came on. They would go off when the engine was above 2k rpms, but the volts stayed below 12.

So the pulley failure might not have been the cause of the initial electrical problem. The alternator is only 1 year old, but it could be bad.

Any other ideas, suggests, or comments would be much appreciated.
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Re: Faulty alternator or charge relay?

Postby proc09 » Tue Sep 25, 2012 10:05 am

This exact thing happened to me a little while ago & it turned out to be that the altenator was fried. The copper wire that is coiled around the outside of the motor & the motor where all burned to a crisp. All the inside of the alternator was black, like it had been on fire. So I replaced the altenator & all is perfect now. I also upgraded to an 80amp alternator instead of going for the standard 50amp alternator. Now I can run my spotties, head lights & stereo all at the same time with no problems. The alternator that fried was the original alternator so to get 20 years out of it I think is pretty good. Although, my MU only has 162,000k's on it so it hasn't had alot of use. It still has the original air con gas in it & it is still cold, I don't use the air con though.
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Re: Faulty alternator or charge relay?

Postby michaelmotes » Tue Sep 25, 2012 2:51 pm

Thanks.
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Re: Faulty alternator or charge relay?

Postby michaelmotes » Tue Sep 25, 2012 3:00 pm

I had two shops do diagnostic tests. One said everything was fine and that maybe a bad ground was causing the lights to come on. But he had no idea why they went off when the RPMs went up. Also when the truck was running, the volts measured by their computer never went above 13 (i remember seeing 12.25). The other also initially said that everything was fine. However, then the manager came over and said that the volts should be between 13 &14, and they were again down in the 12s. So he said that the alternator needed to be replaced.

I just replaced the alternator. Parts stores only sold refurbished ones, so that's what I had to go with. I drove it around the block a time or two, and the dash warning lights never came on. However, the meter in the cab is still showing 12.
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Re: Faulty alternator or charge relay?

Postby michaelmotes » Tue Sep 25, 2012 9:31 pm

We will see what happens with it today.
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