97 SR with A/T: When I hit a bump, the warning lights for the battery, Automatic Transmission (temperature) and brakes all come on. Sometimes they flash and go out, other times they stay on until another bump. Looking at the wiring diagrams, none of these seem to have anything in common other than taking power from the same fuse. That fuse also power other warning lights which do not come on.

Any suggestions!

The dashes ground wires?!

Check the battery hold downs. You may be shorting the posi to ground in the bump.

When mine did this, a simple exchange of the alternator took care of the problem. I also checked for loose wires and other shorts, but it was the alternator.
P.S. - Mine also flashedm, so I didn't immediately assume it was a bad alt.

-Austin

OK, I've checked the battery performance, it is fine. Disassembled and cleaned all grounds affecting the battery, engine, and dash panel. No change. Once the engine warms up, the three affected idiot lights get dimmer, then start flickering on and off- all at the same time- sometimes several minutes between the on and off. Sometimes increasing the electrical load (turning on bright lights, fog lights, and AC)will cause them to light, or get brighter, but not always.

Alternator output (by dash voltmeter) is above 14 v, even with full load.

The original alternator was replaced by a NAPA rebuilt in 2009 (due to the infamous cam seal leak dripping oil). So unless someone has another bright idea, I guess the next step is to replace the alternator.

Hate to spend that much doing a trial-and-error approach to the problem. <img src="/forums/images/graemlins/angry.gif" alt="" />

Check the wiring near your exhaust manifold on the driver side next to the engine. Curiously enough, Carlos had similar issues this evening and we discovered the wires were somehow too close to the manifold and the insulation ended up melting through and shorting out some of the wires (10 or 12 gauge wire which was most likely a main power wire). A surefire indicator would be the main 100amp fuse being blown.

HTH.

When checking the grounds I found the same issue- the wires from the alternator were against the left valve cover just above the exhaust manifold and the black spiral wire cover had melted. The actual wires had the insulation showing signs of melt, but not all the way through. I double checked them, pulled them away from the manifold and valve cover, and added a new spiral cover. However, that did not change the issue of the three idiot lights going on and off.

This is something everyone should look at for the Gen II 3.5 engines. The wire supports do not hold the alternator wire group sufficiently away from the manifold and valve cover.

OK, replaced the alternator and the three idiot lights went out. So, as consistent with some other posts, when the brake, A/T, and battery warning lights all start to light up or flicker at the same time, irrespective of what the voltage gauge shows, it is an indication of a bad alternator or voltage regulator (which is in the alternator).

It remains interesting that there was no indication of alternator output-- when all electrical items were turned on, no dimming of headlights even with brights and fog lights on.

I think your problems were a sign of a diode or three going bad in the alternator. The diodes are like check valves for electricity, and if you get a reverse flow, the charge light for sure will come on, often dim. If you look at the circuit diagrams for the systems you had trouble with, I bet you find a diode in every one.

My FSM electrical shows 3 diodes in the alternator within the rectifier assembly. To test you'd need to get at the rectifier to test continuity or (as it says) use a waveform analyzer. I don't know if you can just replace the rectifier, or if that would be worth doing.