pete c

On the drive home from NY in my "new" 87 Toyota Sunrader (RV on toyota pickup chasis) it started running poorly. Turning the lights on would make it worse. I did not have an ALT light, so I assumed bad ground. My wife who was following me said she saw sparks come out from under the camper. After a short rest, it restarted fine and ran a few minutes more before repeating the problem. I was able to get it to a rest area on the Mass pike and parked it, thinking I could come back the next morning and clean up a few grounds and drive home. I checked the grounds and crawled underneath to look around the area she saw the sparks. I found what I think caused the initial problem. The large gauge coach 12V supply wire was hanging low and laying atop the muffler. The 30 year old zipties were all brittle and broken. Eventually the heat of the muffler melted through the insulation and caused the fireworks. It was at this time I noticed I had no ALT light ever. Not even with the key on, engine off. Voltage at the battery was below 12VDC and no higher while running. I put a fully charged battery in and drove it home.

I downloaded the FSM and it said that no ALT light in the ignition on, engine off state pointed to a bad IGN or CHG fuse, bad fusible link or bad regulator. Fuses/fusible links check good. And if I read the circuit diagram right, losing the IGN fuse or any of the fusible links would result in a dead engine.

I have not yet pulled the alternator (a miserable job on the otherwise very mechanic friendly 22RE). Is there any more I can check prior to yanking the alternator? The FSM did also say it could be a burned out ALT lamp. Is there a way to check this short of pulling the dash apart? I do plan on pulling the alternator off sometime this spring anyway just to give it a good look over. The PO replaced the alternator fairly recently. I assume he used an AZ or NAPA rebuilt which means it is suspect to begin with. I had a 90 V-6 tooycamper that had recently had an alternator replacement and it was flakey. I pulled it apart and found that it had been rebuilt by the world's worst solderer. I cleaned all the solder blob jobs and it was fine.

RAD4Runner

Suspecting bad ground is over-used, but not enough. If you suspect "bad ground" also suspect your 12V positive side connections and wiring. All connections should have bare, shiny metal contacting bare, shiny metal.

You say voltage at battery is below 12VDC. How about AT THE ALT SCREW TERMINAL?
The symptoms suggest many possibilities. This could be because Engine fuse is blown or wiring from it to IG pin of Alt is broken. Or Alt is broken.

Yes. This explains how the 22R-E charging system works. Do the suggested voltage checks at the pins.
Also do voltage checks at these points below.


I took the time to share and annotate check points so so it would make it easier for everybody to help you IF you also noted on diagram what voltages you're getting and shared it with us. Then, we'll go from there.

pete c

Rad4

That is a big help. Thanks!