GENERATOR/VOLTAGE REG

[8543bob]

GOOD MORNING,
I took the M for a ride yesterday and noticed that the volt meter was not showing a charge. i did not have time to open the hood and do a visual. What should I be looking for other than a loose connection?? How do I trouble shoot the gen/voltage reg??
THANKS
BOB

[Tuko]

check and see if the wiring's insulation for the gauge under the dash has frayed and is grounding out on something

[Carter]

Using a VOM check battery voltage with the engine off then with it running, if the genny is operating correctly you should see voltage above the engine off reading, usually around 27.5 to 28.5 vdc. immediately after start-up. This will give you an idea if the charging system is bad or just the vehicles volt meter which could be as simple as a loose wire or bad ground.

Edited
You could also try this:


2. Procedure. When any of the instrument gages, switches, circuit breakers, sending units, or related electrical wiring becomes inoperative, troubleshooting will be accomplished, as prescribed herein, to isolate the defective component or circuit.

3. Ammeter.

a. Check vehicle battery voltage. Charge or replace battery if voltage is not as prescribed in pertinent technical manual.

b. Check position of ammeter indicator hand, with all switches off. Ammeter indicator hand should indicate ZERO position of ammeter dial.

c. Turn headlights and any other accessories ON. Ammeter indicator hand should move to the left (discharge) side of ammeter dial.

d. Turn headlights and accessories OFF.

e. Turn ignition switch ON. Start and run engine at approximately 1,200 rpm. Ammeter indicator hand should move to the right (charge) side of ammeter dial.

f. If ammeter does not conform to reading outlined above, proceed as follows:

(1). Check generating system for amperage and voltage output, as listed in vehicle technical manuals. Adjust or replace components as necessary as prescribed in pertinent technical manuals.

(2) Disconnect either wire from ammeter and connect it to the positive lead of a voltmeter and ground the negative lead of voltmeter. Voltmeter should indicate battery voltage.

(3)Disconnect wire from voltmeter and connect it to ammeter.

(4) Disconnect the other wire from ammeter and perform the same test. If either or both wires do not indicate battery voltage, repair or replace voltage regulator or ammeter lead as necessary. Caution: The circuit from the voltage regulator to the ammeter is not protected by a circuit breaker. Therefore, when removing wires from ammeter do not allow them to contact vehicle ground as damage to the wires will occur. If ammeter does not conform to readings indicated above at conclusion of tests, replace ammeter as prescribed in pertinent technical manual.

[8543bob]

THANKS GUYS, HOPEFULLY I'LL GET TO IT THIS AFTERNOON. THE BEACHES HERE JUST OPENED TO OFF-ROAD VEHICLES, I WANT TO GET TO THE OCEAN AND CATCH SOME BASS.
AGAIN THANKS
BOB

[Carter]

Correction, should have posted this volt meter info instead of ammeter I put up before, sorry.

Battery Indicator (volt meter)

a. Check vehicle battery voltage. Charge or replace battery if voltage is not as prescribed in pertinent technical manual.

b. With ignition switch OFF battery indicator should bear to extreme left side of dial.

c. With ignition switch ON battery indicator should move to the yellow portion of the dial.

d. Start and run engine at approximately 1200 rpm or higher, battery indicator needle should move to the green portion of the dial.

e. If battery indicator does not conform to reading outlined above, proceed as follows:

(1) Turn ignition switch OFF.

(2) Disconnect wire at battery indicator and connect it to the positive lead of a voltmeter. With the negative lead of the voltmeter grounded and the ignition switch ON, voltmeter should indicate battery voltage.

(3) Start and run engine at high revolutions per minute, voltmeter should indicate generator voltage charge as specified in vehicle technical manual.

(4) If voltmeter does not indicate generator voltage charge as specified in vehicle technical manual, adjust or replace components of the generating system, as necessary, as prescribed in pertinent technical manual.

(5) If voltmeter indicates generator voltage charge as specified in the vehicle technical manual and battery indicator does not conform to test in a through d above, replace battery indicator as prescribed in pertinent technical manual.