GP(R) Testing
Post Fiend
Joined: Nov 2007
Posts: 9,549
Likes: 14
From: Payson, AZ
best way to check GP function is with an AMP guage. If you have access to an inductive AMP meter simply clamp around the wires coming off the output terminal. On a cold engine you will see 192 Amps if all the GP are working correctly. The Amp draw will taper off the longer you leave the key on. you can then check individual sides by clamping around only one output wire. this can help decide which side the bad ones are on.
12v may be passing through the relay but if it won't handle the amps, its not going to work correctly.
Barney
12v may be passing through the relay but if it won't handle the amps, its not going to work correctly.
Barney
Rep sent.
Post Fiend
Joined: Nov 2007
Posts: 9,549
Likes: 14
From: Payson, AZ
From the Ford service manual.
The 7.3L diesel engine uses a glow plug system that preheats air in the combustion chamber to improve cold engine starting.
The system consists of:
glow plugs.
glow plug relay.
glow plug module ( CA Trucks and Excursions)
powertrain control module (PCM).
engine oil temperature (EOT) sensor.
barometric pressure sensor (BARO sensor).
The glow plug system is electronically controlled by the PCM. If the oil temperature is below 131°F (55°C ) the PCM will energize the glow plugs immediately after the key is placed in the ON position. Then, depending on the readings from the engine oil temperature (EOT) sensor and the barometric pressure (BARO) sensor, the PCM determines how long the glow plugs will be on.
Glow Plugs — PCM-Controlled
The glow plugs are located in the cylinder heads, under the valve covers.
The glow plugs are self-regulating. If the engine oil temperature is above 131°F (55°C ), the PCM will bulb-check the WAIT TO START lamp but not energize the glow plug relay or control module.
The PCM system uses the glow plug module (if equipped) to conduct current to the left and right bank glow plugs.
The PCM protects the glow plugs by energizing them for short durations if the battery voltage is abnormally high.
The glow plug ON time varies from 0-120 seconds depending on battery voltage, engine oil temperature and barometric pressure.
On California vehicles the glow plug monitor (GPM) system is part of the On-Board Diagnostics II (OBD II) System.
The GPM system is designed to find failed glow plugs or failed wiring in the glow plug system.
A failure in the glow plug system will set a diagnostic trouble code (DTC).
Thread
Thread Starter
Forum
Replies
Last Post
Blueovals&Blacksmoke
Pre-Power Stroke Diesel (7.3L IDI & 6.9L)
5
Sep 25, 2008 06:22 PM
mjnoakes
1999 - 2003 7.3L Power Stroke Diesel
1
Dec 16, 2003 02:36 PM
