Re: '91 Accord LX 2.2L 5-spd manual wagon, Battery Light On, Shop Manual diagram Wrong??

While trying to trace a problem with the Battery Light staying on, I noticed a discrepancy between the shop manual and the car itself. The shop manual (page 16-93, attached) shows the alternator's S terminal (regulator sensor) connected through the No.21 (7.5A) fuse in the underhood fuse block to the main 80A fuse (No.15). BUT, the car itself shows this fuse is a no load on the fuse label.

So... Where in the world does the WHT/GRN wire go to from the S terminal if not fuse No.21??? Some have mentioned here that there may be a relay above the glove box. Can't seem to find that, but I assume it's one possibility. Also, is there only supposed to be a reference voltage at that terminal when the engine is actually running? (I get none in either case, ignition on or running, but half of that could be intended operation before starting.)

Symptoms & Things I've Tried:
- Battery light on constantly
- The No.2 fuse (15A) under the dash is good.
- The car will start and run but only off of battery voltage.
- With key on / engine off: BLK/YEL shows battery voltage @ IG terminal, WHT/BLU shows battery voltage @ L terminal, WHT/RED shows nearly 5V at FR terminal (for fuel injection), BUT...
- I'm not getting any reference voltage at the S terminal either when the ignition is on, or when the engine is running.
- SEEMS LIKE WHT/GRN IS OPEN!!! No connection seen w/ ohm-meter at fuse No.21 in underhood fuse block. Very difficult to trace this wire! (Again, where does it go?)
- No charging is occuring when running (I only read battery voltage at the B terminal, not ~13.5 or greater).
- I do have good connectivity from B terminal to battery positive through a good 80A fuse.
- I do have good connectivity from Alternator case to battery GND through the chassis.
- I tried making the connection as specified in the shop manual's diagram with NO change in symptoms. Guess I'll back that out since it didn't seem to solve anything.

Things to try still:
- I haven't pulled the alternator yet to take it in for testing, but will today.
- Check the pulleys to ensure the rubber bond isn't broken or slipping
- Get voltage measurements at each terminal while running (I've only tested w/ ignition key on so far).

So, aside from any other suggestions on what to try, I guess my main questions are:
1.) What's the real deal with the wiring since the shop manual appears to be wrong?
and 2.) Is there some relay that's part of how it's actually wired, and if so where can it be located more specifically than "above the glove box"?

A million thanks to all who respond!!!

--Mike

 

here are the diagrams i think you are looking for.

 

Thanks Jeff! Yep, those look much better. Interestingly enough, the S terminal was renamed C and appears to be an output of the alternator rather than an input. Not sure why my manual was different, but this clears it up. Thanks again.

Diagnosis: After going through a more thorough test procedure, I found that grounding the F terminal to force full field resulted in proper alternator output. This proved that the voltage regulator was bad and I didn't need a new alternator. $28 for a reman. regulator off of eBay rather than $95 at the parts store for the entire alternator... Yay!!

FYI for anyone else who finds this post, testing an alternator with no charging to see if it's the alternator or the voltage regulator is an easy procedure and should probably be done first before diving in too far. Simple connect your multimeter to the battery measuring the voltage, start the engine, then insert a small screwdriver into the F Terminal hole in the back of the alternator casing and make sure it touches the case to ground the terminal. If the alternator is good but the regulator bad you should then see charging at the battery where there was none before, ie- the voltage should rise. I saw a steady 14V at this point. Rev the engine a bit and you'll see it rise further, drop some loads on the engine (defogger, blower motor, headlights) and you'll see it fall a bit. I was careful not to exceed about 16-18 volts so nothing in the electrical system would get fried.

 

good job, glad ya got it fixed!