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Strange confluence of electrical issues in '99 4runner. Can anyone help diagnose?

I have a 1999 4Runner and have been experiencing electrical issues. It would be great to get a lead on what the problem is to see if I can fix it myself without going into a shop. Here’s some relevant information:

  1. The electric locks always work when the car is running but after turning the car off they sometimes work and sometimes don’t. When they don’t work I can hear the lock motor turning, just not putting enough force to actuate the lock mechanism. Sometimes waiting a few minutes works, sometimes I need to manually lock the doors. (Voltage issue?)

  2. When the car is running and I turn on the headlights the interior lights dim and sometimes the stereo system briefly turns off as if there was a significant voltage drop. The stereo always turns back on a few seconds later and the lights always brighten again. The same thing (stereo restarts) happens sometimes when I am going slowly and then give the car gas, but only early on in a trip.

  3. Sometimes after driving and parking and sitting for an hour or so the car won’t start at all (won’t even crank). Depressing the brake pedal resolves this issue. Crazy, I know. I had the front brakes done by an unfortunately shoddy brake shop a few months ago. Related?

  4. The starting battery is two years old and reads 12.6 after sitting overnight. The car almost always starts quickly and easily. After starting the voltage at the battery slowly goes up, leveling off around ~14.2. Immediately after starting the car the voltage at the battery reads around 13v but the voltage at the cigarette lighter reads ~14.4. (Perhaps the cig lighter is fed directly from the alternator?)

  5. I removed the fusible link from the cigarette lighter a few months ago (before problems started) but didn’t notice any problems immediately afterwards and am not sure how those could be connected.

  6. A remote entry / alarm system is installed. Sometimes the remote unlock works and other times it doesn’t. I never use the remote lock anymore because it arms the alarm system and I’m never sure that I can disarm it by clicking “open” on the key fob.

  7. A couple of weeks ago I went to pick a friend up at the airport and sat in the cell phone lot with music playing and my phone charging off of the cig lighter for about 20 minutes. The engine was off but I had been driving for a half hour before I parked. When I tried to start the car afterwards the battery didn’t have enough charge and I needed a jumpstart.

Okay, enough monologue. Electrical geniuses, what are your thoughts? Fingers crossed that the internet can figure this one out!

Get a new battery. Go for the most Cold Cranking Amps, CCA available.

Whenever having electrical issues for the most part it is always a good step to first clean the battery connections, even if they look okay. When reconnecting the clamps do not overtighen them. If that doesn’t fix the problem then look for connection problems in the power distribution panel. Have a load check done on the battery to check the condiiton of it and also on the alternator to make sure it is working okay.

There could be a ground problem causing the trouble. Clean the battery to chassis ground connection.

I would check and clean all battery connections and make sure the cables aren’t corroded near the connectors.

If all connections and cables are good I’d get the battery and alternator tested.

To check the no start I would use a voltmeter to see what voltage is at the starter when it starts and when it doesn’t. If it is the same then it could be a starter or starter solenoid problem. How old is the starter? Bad solenoid contacts are a common problem with Toyotas and cause an intermittent no start.

If the voltage is low on a no start then it could be a problem with the brake interlock, the neutral/park interlock, or the ignition switch.