I've had a few problems after driving my longsuffering 1997 RAV4 on a bad dirt road including a shallow river crossing, and I think they're related and something to do with the electrics, but I can't figure out what they mean:
- A couple of times when steering slowly at night, particularly reversing into my driveway, the steering locks or freezes for a second and then is very heavy. Some research suggests this could be the electric power steering motor cutting out because it's not getting enough power with the headlights, brake lights etc all on (and possibly a passenger using the power windows, I don't remember)
- The stereo has started misbehaving, sound quality degrading to crackles after a few minutes use and intermittent cutting out. Some research suggests this is associated with struggling alternators.
- Sometimes when starting the engine, there's a whistling or whining sound for several seconds, similar to an old style kettle or steam engine pressure valve letting off steam but oscillating. Some research suggests this could be the alternator or power steering motor whining, and it seems to come from the right direction for both. It's intermittent and hasn't happened with the bonnet up to identity more precisely.
- I think the headlights are slightly dimmer and power steering slightly slower than usual but I could be wrong about these.
So I was expecting to find a slipped alternator belt or evidence it was failing and outputting low voltage, but I found something else:
- The belts were fine and spinning fine with the engine at idle
- The voltage at idle was 14.7, higher than expected. Didn't change while revving
- I'm also not sure if this is "a little higher than normal but within the tolerable range" or "a seriously abnormal sign of a serious problem", different sources seem to contradict each other on this
- The voltage of the battery itself with the negative terminal disconnected was 13.7, higher than expected. The circuit with the engine off was lower but less than 0.1 volts lower, within rounding. Something like 20 minutes after idling the voltage was down to 13.4 but still higher than expected, then immediately after running the engine again, it's back up to 13.7
- Again, I'm not sure if this is "a little higher than normal but within the tolerable range" or "a seriously abnormal sign of a serious problem", different sources seem to contradict each other on this
- With the battery connected and engine off, if I connect my multimeter negative cable to one particular spot (the steel air conditioning high pressure tube), it gives an unexpected voltage of about 0.4 volts which disappears when I disconnect the battery negative terminal. I'd expect either the same voltage as everywhere else, or zero. With the engine running this strange other circuit is something small like 0.03 volts higher
I feel like all this things seem related but I'm not sure how since it's the opposite of what I expected. What further tests can etc can I do? And are there any urgent things I should worry about e.g. Battery acid overheating?