Voltage Regulator or Battery issue?

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Dprio34

Dprio34

10 Year
Joined
Oct 2, 2015
Threads
36
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794
Location
Las Vegas
Website
forum.ih8mud.com
Condition: 2L-T or TII in an LJ70 after a very extended drive (400kms), then put the vehicle to rest for the night.
The next day, the battery icon on the voltmeter blinks and both green and red lights on the RPM gauge blink after startup and up to 2 hours of continuous driving.

Sometimes this is accompanied by large irractic swings on the speedometer and sometimes it is not.

The blinking lights (green, red, battery icon) usually stop after and hour or so, but the irractic speedo may last an entire 200-300km into the extended drive.

This only happens on longer roads trips on the second day of the trip after start up.

If anyone has any ideas what is gong on, please let me know. Thanks.

Battery is older, but has over 12 volts on it, alternator has been rebuilt (this condition existed prior to rebuild and continues after). This is what leads me to believe it is the VR but would like some input prior to a purchase.
 
Last edited:
Ok the speedo is driven by a cable... its not electronic... So only way it to swing is there is some drag on the cable or something in the instrument cluster is interfering with its operation. (dirt, bugs)

As for alternator... Check voltage with engine off..... Should be 12 v plus...
Then start her up and check voltage again ... should go upto 14v plus.
If not the alternator is not charging...Could be the VR ... Not sure if its internal to the alternator or a separate unit in that model.

Sometimes the diodes in the alternator start to fail and they can back feed voltages and trigger all sorts of electrical gremlins. Warning lights flickering, or on solid.
 
Calvin,
Thanks for the input.
Yes mine has the external voltage regulator (mounted on the right hand side , inside fender).
Battery voltage checks as you describe.
 
Well,
I was "thinking" and sometimes I don't do that very well, that the two lights I the RPM gauge (green and red) blinking along with the battery icon blinking, was some type of "excessive" charging indication that Toyota built into the electrical system. I looked though the manuals I have but cannot confirm this. But for some reason I suspect this. Sort of a cheap ammeter. Just probably a wrong hunch on my part.

I will get a new battery. If that doesn't solve the problem, I will get a new external VR. Process of elimination I suppose.

Strange thing is, the erratic speedo indications always follows the "blinking" - I never get either problems daily driving around town, just on long road trips, far from home. Unnerving to say the least.
 
Check all the cables & connections around the alternator, regulator & battery. Loose alternator connections can make many different warning lights all come on at once - quite confusing the 1st time you see it. Erratic speedo at the same time is weird though, maybe your model has an electric speedo?? - Calvin is right that most if not all 70 series have cable speedos though.

Cheers
Clint
 
I recently wasted a lot of time and effort tracking electrical faults.
Buy nothing yet.
Go to an auto electric shop, the kind of place that repairs starters, alternators and not much else.
They can test all sorts of things on the spot, usually without an app't.
If older guys work there, that is good.
 
Had the speedo freakin out. It came out it had dirt inside the speedo , possibke dried vaseline??? Carefully cleaned that and its fine. I had to take the speedo apart, be extremely carefull not to touch the dials with fingers.
 
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