Regula high voltage spike

Anomer

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Jun 6, 2015
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My Troopie (2000 4.5L EFI) has developed a problem. A high voltage spike seems to be generated at regular intervals of about 100 s. It manifests itself in the windscreen wipers activating once and a momentary cut-out of power to the console (needles on speedometer and rev counter dip then return to notmal and on several occasions the trip Odo's have zeroed consistent with battery disconnection). I have an electronic "fusible link" which may be reacting to the spike. I only know its a high voltage spike as my UFH radio has an alarm for high voltage and occasionally has comes up with the message "High DC" when it happens. This spike is very regular at about 100 s and follows an audible click (not sure from where) by about 32 s. These observation were at a constant speed of about 100 km/h and 2000 revs. Unfortunatley it doesn't generally happen at idle although has done occasionally. We are on an outback trip and seemingly the performance of the vehicle isn't affected, as we have had no choice but to drive hundreds of kilometres with this happening. On several occasions the problem resolved during the journey. Have to sort this out prior to continuing on our big trip, so are stuck in Darwin. Can anyone shed light on this before I tackle an auto-electrician or Toyota workshop.
 
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grantw

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I think there are two main possibilities a bad earth or the alternator voltage regulator.

Check all battery connections & earths on the engine block and chassis. If they look to be ok then get the alternator bench tested.
 

StarCruiser

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Does your troopie have a solenoid type fuel pump? I'm guessing by the age that it won't, but just a thought. The other possible is if you have AC and the magnetic clutch is kicking in and out. Sounds to me like 'back emf' from a solenoid coil.
 

Anomer

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I am in australia
Jun 6, 2015
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I think there are two main possibilities a bad earth or the alternator voltage regulator.

Check all battery connections & earths on the engine block and chassis. If they look to be ok then get the alternator bench tested.
Thanks. Will check these but am baffled by the regularity of the spike. Would a fault in the alternator not materialise at different intervals depending upon the revs. It doesn't seem to.
 
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Anomer

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I am in australia
Jun 6, 2015
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Thanks. I will check the fuel pump type. Re the AC, the problem materises with the AC off. We eliminated other factors like windscreen wiper unit itself by disconnecting them. With the wiper motor unplugged naturally there is no wiper action but the problem was still there. In fact in this case, the console seemed to flash briefly. I think the w/screen action acts to absorb most of the extra energy.
 

StarCruiser

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It could be a relay, though not quite sure why it would give trouble as any back emf would be small and I'm not aware of relays having any freewheel diodes or other protection. Not sure what the Troopies have that would give that regular 100 seconds blip. Sounds like something coming on every 100 seconds and going back off again 32 seconds after that.

This rather discounts my theory on the fuel pump being a solenoid one as that would be a pulse. This has an on followed by an off when you get the spike.
 
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Dave 2000

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Wear in the alternator bearings (usually rear one) can cause this. As the three parts of the bearing rotate there tends to be an interval where there is severe wear. When the three line up the armature moves out of centre, often allowing the slip rings in the casing to touch. Only seen it twice and neither occasion on an 80 but worth a look?

Also, assuming you have a spare battery, try running for half an hour with the alternator disconnected, if there is no weird voltage spikes you have found the problem.

regards

Dave
 

Anomer

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I am in australia
Jun 6, 2015
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Hi Grant,
Not as yet. As per my reply to the post above (what do you think of Dave's thoughts?) we left the vehicle in Darwin and I will be returning on 7th July to (hopefully) continue our travels after we have had it looked at by an auto-electrician. I will be conveying your and other's thoughts to the a-e. Certainly will relay the outcome once we sort this out.
 
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Anomer

New Member
I am in australia
Jun 6, 2015
7
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Hi Dave,

That sounds very plausible and it would explain the time interval. The vehicle is in Darwin at present and I will be taking it to an auto-electrician upon my return early July. Certainly will convey your views to them. I have a spare battery in the vehicle so thats also worth a try. Many thanks
 
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