Join Date: Dec 2008
Location: Tyler, TX
Thanked 407 Times in 347 Posts
Check the Glow Plug Relay.
Get a MULTI METER - Digital is BEST and no a "test light" will NOT work. Place it so it can be seen from inside the cab (like resting on the hood/cowl panel). Set the meter to read at least 12V (15V or 20V is better).
1) Test for a good voltage and ground TO the GPR:
- Place each of the leads on one of the SMALLER teminals of the GPR.
- Voltage should be about 0v with the key OFF.
- Turn the ignition to "RUN",
- With the WTS light ON, you should read about 10v to 12v on the meter. If so, the GPR power and ground control circuits are working and the GPR *should* be supplying power to the GPs.
2) Test GPR function:
- Place one lead of the MM on each of the LARGER terminals on the GPR.
- Set the MM to read between 0v and 12V (20 is fine too).
- Turn the ignition to "RUN", WHILE the WTS light is ON, note the voltage shown on the MM.
- Voltage MUST be between 0V and 1V (ignore the "-" sign if you see it), anything else = BAD.
3) Test GPR main power (if everything checks ok to here):
- Connect the BLACK wire from the MM to BATTERY ground (DO NOT use ANY other ground).
- With the ignition OFF and the RED wire of the MM, find out which LARGER terminal is "always hot", connect it there.
- Turn the ignition to "RUN" and with the WTS light ON read the MM.
- If the indicated voltage is 10V to 12V the power to the GPR is good.
- If the voltage is LOWER than 10V do step #4
4) Check battery power and grounds:
- Connect the BLACK lead of the MM to BATTERY GROUND.
- Connect the RED lead of the MM to an ENGINE GROUND.
- Turn the ignition to "RUN".
- With the WTS light ON, note the voltage on the MM.
- 0v to 1/2v (0.5v) = GOOD ground to the engine.
- 1.0v or more = BAD GROUND to engine.
- If everything is in spec, do #5.
5) Check batteries:
- Connect BOTH MM leads to a BATTERY terminal.
- Turn the ignition to "RUN" and with the WTS light on you should get 10v to 12v (9.6v is the MINIMUM allowed).
- Ensure the MM and leads are CLEAR OF MOVING PARTS!
- Turn the ignition to "START".
- MM should indicate 9.6v MINIMUM.
- Less than 9.6v during cranking = bad battery (or two), undercharged system (alternator or worn down from previous cranking or dome light etc), or bad connection of meter leads.
'93 F-250 HD, 7.3L IDI, 5spd - FARM TRUCK
I Support: Trailer brakes an every axle over the towing vehicle's GVW; CDLs for RVers; Safety inspections for ALL vehicles and 6 axle trucks (97K GVW proposal).
Democracy is two wolves and a lamb voting on what to have for lunch. Liberty is a well-armed lamb contesting the vote - Benjamin Franklin
I vote for LIBERTY!