Yet another electrical gremlin

[rule303]

Need some help from some of you knowlegeable folks out there. I took one of my rare drives in my 99 LC today, just to check on how its running and run a few errands. Noticed the battery idiot light flickering and coming on briefly then going off. Also noticed the volts read too high on the meter when the light came on and then read normal when the light went off. So it sounds like a high voltage situation. Volts are peaking up towards 16 or so I'd guess. Voltage regulator perhaps? I just had a new battery and alternator installed a few thousand miles ago. Could it be a bad alternator? Or could this problem have lead to the premature demise of the old alternator. My wife is not the type to notice blinking lights on the dash, so it could have been an old problem.

 

[mobi-arc]

Make sure the connections between battery, alternator, and harness are all tight. Then, with the engine running at elevated RPM's (say 1200), use a digital multimeter and check voltage on the battery, both on the cable termination, and on the post. If it's north of 15v, or if it's bouncing around, it could be voltage regulator or sloppy connections. If it's stable and north of 15v, it's likely a regulation sense issue being thrown off either by resistance or a poor connection. If it's +/- 18v, it's unregulated and the regulator is popped. Also, have the battery load tested to insure that's not the problem. Hope this gets you headed in the right direction.

Scott

 

[rule303]

I cleaned the battery posts as well as the clamps. Would an OVER voltage situation be caused by bad connections. I can understand how an under voltage can occur. My guess is its the new alternator I had installed.

 

[mobi-arc]

If the "sense" connection is off due to resistance, the regulator will compensate with a increased voltage output thus causing an overvoltage setpoint. In other words, if the regulator's setpoint is 14.5, it will increase the alternator's output to regulate 14.5. If the "sense" connection were .5 volt off due to resistance, the regulator is causing the alternator to generate appropriate output until it sees 14.5 on the sense connection. If it's .5 volt off, the actual output would be 15 volts to the battery thus yielding 14.5 volts on the sense connection. In that situation, the regulator is functioning correctly, it's the resistance on the sense connection which is causing an overcharging situation. You have three things to look at: alternator, battery, and wiring/cabling between the two.

 

[rule303]

I understand now after what you said and what I've read. Thanks for your help btw. I went through the vehicle checking every ground to the body and I will continue to check connections. The damn alternator is so hard to reach though. I drove it again today and it is doing ok so I think I may have fixed it. Another reason not to buy a norther car with salt corosion. Its light, but every dang connection has some corrosion.

 

[rule303]

Well its acting up again. Moving up to 16 volts or so for a few seconds then back to normal.
Only does it sporadically and never for very long. Its a new battery so I don't thing thats the problem. I'm going to take it back to the folks who installed the alternator and let them sort it out.

 

[Kanab]

Well its acting up again. Moving up to 16 volts or so for a few seconds then back to normal.
Only does it sporadically and never for very long. Its a new battery so I don't thing thats the problem. I'm going to take it back to the folks who installed the alternator and let them sort it out.

Based on the number of electrical problems you are having I was just wondering if your LC has ever been in deep water?

 

[rule303]

I don't think so, but it does have some minor salt corrosion under the hood. NEVER buy a northern vehicle. My first and last. I bought it on Ebay. I've bought quite a few on Ebay before and never had a problem. This SOB dealer lied through his teeth when I specifically asked him about corrosion. He had 200+ perfect feedback so I trusted him. He even gave me $1000 not to slam his feedback but I took the money then gave him a reaming on the feedback anyway. Asked him how it felt being lied to. He still has potential buyers emailing me to ask questions, so that one lie has probably cost the guy thousands in lost sales since then. Car salesmen are pathological liars. They'll never tell the truth when a lie will do. Other than the corrosion, the vehicle is in great shape, but I'm an electrician and I know what trouble corrosion can cause with connections. I really haven't had that many electrical issues. Really just the alternator and the TPS, which many have had. Its the alternator on the bottom side of the engine that the salt could have gotten to and caused issues. I'm putting it up for sale tomorrow. Defeats the purpose of buying a Toyota to have all these nagging issues. And mechanics around where I live act as if its some exotic car or something. Parts are absurd too. My first and last Toyota probably. The horrible dealers soured me on buying Toyota again and there isn't an independent shop within an hour who can work on them. Bad side of living in a rural area I guess. I've had the LC in for work at least 5 times in 3 months! I didn't have my old Expedition in that many times in 3 years. I know I probalby just got a lemon. But there are some design issues on these vehicle that bother me.

 

[mobi-arc]

I agree that placing the alternator low is retarded engineering, especially in a vehicle with off-road capability.

 

[rule303]

That and the starter being buried under the intake manifold. The throttle relying on a motor control and several sensors and when any of them fail your'e stuck. Check out the electrical connections deep behind the engine and the goofy fuse block right on the battery. Tons of stuff like that leave me unimpressed somewhat with Jap engineering. Hardly things easily fixed in the woods. The 80 series were probably the last of the great off road cruisers. The 100s are just nice suvs. The lack of power seat memory also drove me crazy. $60,000 and they couldn't figure that out? A real problem for us who share the vehicle with a 5ft woman.