How to reset pcm 1995 gmc 6.5 1ton chassie on rv

Don't just keep cranking if it don't start right away' Give the starter a break. It's getting hot because you just keep cranking on it. Any vehicle diesel has glow plugs to heat the fuel chamber to make it start fast. Be sure you are making use of the glow plugs and it will start fast. If your glow plugs are not working, find out why. Could be just the glow plug relay or connection to it. Or possibly the glow plugs are burned out. Either way, you HAVE to have glow plugs in use on a diesel upon initial start up till it's warmed up. Then will start without them. Most are automated system. You just have to wait till the glow plug light goes out to start cranking on it. I hope this helps you to more understand the workings of a diesel cold start system.

You should never use starter fluid when the glow plugs are hooked up. It can cause severe engine damage. You probably need to replace all the glow plugs and the glow plug controller.

Have fuel pressure checked and scan the system for fault codes.

sounds like a glow plug problem,if it starts o.k. when warm,but not when cold,does it smoke a lot when trying to start it cold,if so i would say your glow plugs are either burned out or theres no power to them when you turn on the key,do you see the glow plug light on the dash,it may light,but that doesn,t mean the glow plugs are getting power

I had starting problems and found the fuel filter was pulling air through the seal.Replaced fuel filter with genuine Chrysler part and this fixed the problem.

Hello Charles: My name is Roger and I Will help. The PCM is located behind the glove box on top of the heater case. The VCM is located under the hood just above the ABS unit. Should you need further help please just ask. Please rate the answer you received. This way I know the answer was helpful. Thank You for using Fix Ya. Roger

drain water from filter. change filter. prime system.
If it doesn't fix it, check glow plugs to be sure they are preheating combustion chamber.

Fuel Supply System The fuel system consists of the following three major subsystems:

• Fuel supply system
• Injection control pressure system
• Fuel injector assembly

The fuel transfer pump is a camshaft-driven, two-stage diaphragm/piston pump mounted in the engine "V".
Fuel is drawn from the fuel tank through the primary filter by the diaphragm section of the transfer pump. Pressurized fuel (approximately 28 kPa [ 4 psi]) is supplied to the secondary filter and returned to the second stage of the transfer pump. The piston-actuated second stage of the transfer pump supplies 276-345 kPa (40-50 psi) of fuel to the rear of each cylinder head where it flows to a fuel rail machined in each head.
Drillings in the cylinder head route the fuel to the plunger area of the fuel injector which can pressurize the fuel to 124,110 kPa (18,000 psi) for delivery to the combustion chamber via a conventional nozzle/valve tip arrangement.
Return fuel is plumbed from fittings at the front of each cylinder head to a junction block which contains a piston/spring type regulator valve that maintains pressure to approximately 414 kPa (60 psi). A de-aeration bleed orifice between the fuel filter and the regulator block vents air trapped in the fuel filter. Most of the fuel from the regulator is recirculated to the inlet of the piston (high pressure) stage of the transfer pump. Fuel return to the tank is limited to 30-38 liters (8-10 gallons) an hour through the use of a 0.0008mm (.020-inch) orifice. This prevents the fuel from overheating in the tank.
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Injector Driver Module The injector driver module (IDM) is used in conjunction with the PCM to sequentially control power to the fuel injectors on the 7.3L DI turbo diesel engine. The PCM processor generates two digital control signals for the IDM: fuel delivery control signal (FDCS) and cylinder identification (CID). The FDCS signal is used by the IDM to control injection timing and injection duration. The CID provides synchronization to the engine's first and fifth injector (firing order). The IDM verifies that FDCS and CID occur at valid timing intervals. The IDM outputs an electronic feedback (EF) signal, to the PCM, which is a delayed mimic of the FDCS for verification. Selected diagnostic information is also passed to the PCM via the EF signal in run mode.
The IDM is a high-energy power supply which acts as an energy distributor to provide regulated injector energy and control to the unit fuel injectors, based on FDCS and CID commands from the PCM. All IDM components are solid state; there are no user serviceable parts or adjustments. The IDM internal power supply uses a DC-to-DC converter to boost the supply voltage (VBATT) up to 115V DC. This supply is required to overcome the initial impedance of the injectors, ensuring rapid turn on. There are two high side drivers, one for each bank (left and right cylinder bank), and eight low side drivers, one for each injector. One high and one low side must be turned on to energize an injector. Once synchronized with the PCM, the IDM will select the proper low side driver (enable) and control the corresponding high side driver to regulate the current to an injector.
Continuous and on-demand system diagnostic information is provided between the PCM processor and the IDM via the EF signal. During normal operation, the IDM can indicate to the PCM that an injector low side short to ground has been detected, or that the IDM has lost synchronization.
The IDM constantly performs self-diagnostics and also monitors the injector circuits for electrical faults. Any fault codes set are transmitted via the EF signal to the PCM during Key On/Engine Off On-Demand Self Test. If the PCM is unable to obtain diagnostic information from the IDM, DTC 1668 is set.
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Glow Plug Control Glow plugs are used to warm the cylinders to improve cold-engine starting. The PCM uses the engine oil temperature (EOT) sensor and barometric pressure (BARO) sensor to determine how long the glow plugs will be on. The PCM energizes the glow plugs longer if the engine is very cold or if the barometric pressure is low at high altitudes.
The PCM controls the relay that supplies power to the glow plugs with the glow plug control (GPC) signal. When the GPC signal is grounded by the PCM the relay closes, turning the glow plugs on.
The glow plugs are controlled by the following sequence:

1. PCM energizes the glow plugs.

1. The PCM energizes the glow plugs immediately after the ignition is placed in the ON position.

1. The PCM then determines how long glow plugs will be on based on EOT sensor and the BARO sensor. The required time to warm up the cylinder decreases the engine oil temperature and barometric pressure increases at low altitudes.
2. ------------------------------------------------------

Glow Plug Lamp Control The glow plug lamp (GPL) signal controls the WAIT TO START light located on the instrument panel. This light is used to indicate when to start the engine. The cylinders are being warmed by the glow plugs during and after this light is lit. The PCM energizes the glow plug lamp longer if the engine is very cold or if the barometric pressure is low.
When the GPL signal is brought low, the "Wait to Start" lamp is turned on.
The glow plug lamp is controlled by the following sequence:

1. PCM lights the WAIT TO START light after a key on reset occurs.

The PCM determines the glow plug lamp activation time based on engine oil temperature, barometric pressure and battery voltage.

1. PCM turns off the WAIT TO START light.

The glow plug lamp is turned off when the timer counts to the number of seconds specified by the PCM. The glow plugs will normally remain on longer than the "Wait to Start" lamp.

if you need connectors and terminals for the glow plug connections under the valve cover, Ford sells then so you don't need a whole $600 harness.

info for your use

Section 03-07B: Glow Plug System 1996 F-250, F-350, F-Super Duty Equipped with 7.3L Diesel Engines Workshop Manual
DESCRIPTION AND OPERATION Glow Plug System The 7.3L diesel engine uses a glow plug system which preheats air in the combustion chamber to improve cold engine starting. The system consists of eight glow plugs, the glow plug control module (12B533), powertrain control module (PCM) (12A650), engine oil temperature (EOT) sensor and barometric pressure sensor (BARO sensor) (12A644). The glow plug system is electronically controlled by the powertrain control module. The powertrain control module energizes the glow plugs immediately after the key is placed in the ON position and then determines how long the glow plugs will be on according to the engine oil temperature and the barometric pressure. The required time for the glow plugs to be energized decreases as the engine oil temperature and barometric pressure increase. The glow plugs are self-regulating, and the powertrain control module controls relay ON time. The powertrain control module protects the glow plugs by energizing them for short durations if the battery voltage is abnormally high.

Possible Causes: Insufficient glow plug ON time will not allow enough heat to accumulate in the combustion chamber to easily facilitate starting. If the glow plug system ON time does not meet any of the specifications in the accompanying chart the problem is most likely a faulty wire harness connection, ground connections or glow plug relay.

If the glow plug resistance to ground is high, the most likely causes are an open UVC (under valve cover) harness or open glow plug.
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Relay Operation
Install a DVOM on the glow plug feed side of the glow plug relay (large stud with two wires connected). Turn the ignition key to the ON position but do not attempt to start. Note the time in seconds from when the key is turned on and the glow plug relay energizes until the glow plug relay de-energizes. The glow plug relay makes a loud click noise which is easily heard when it energizes and de-energizes. The dome light will dim and the dash voltmeter will dip when the glow plugs are drawing current from the battery. Compare the times measured to the table (time will be affected by engine temperature, battery condition and vehicle altitude). The voltage at the glow plug feed terminal may vary from 9 to 12 volts depending upon battery condition.
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If battery voltage not present check for B+ at power supply terminal (terminal with single large wire). Power for glow plug power supply is supplied from starter relay through two fusible links at solenoid.
Glow Plug Operation
Disconnect all of the glow plug/injector harness connectors from the valve cover gaskets. With the pigtail installed, measure glow plug resistance to ground (preferably B-). A resistance measurement of .1 to 6 ohms indicates a good glow plug.



Glow Plug Harness Continuity
Measure for continuity from the connector harness to the glow plug feed terminal on the glow plug relay. Resistance should be less than 5 ohms.
Incorrect measurements will result if all glow plug/injector connectors to valve cover are not disconnected.

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Glow Plug Relay The glow plug relay (12A343) has a plastic base and two mounting bolts. It is operated by the powertrain control module (PCM) (12A650) which senses engine oil temperature, PCM voltage and barometric pressure. When the engine oil temperature or the barometric pressure is low, the PCM activates the glow plug relay and the glow plugs. If the PCM voltage is too high, the powertrain control module deactivates the glow plug relay and the glow plugs immediately energize for a shorter duration, decreasing the modulation of the duty cycle.
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Glow Plug Removal

1. WARNING: THE RED-STRIPED WIRING HARNESS CARRIES 115V DC. SEVERE ELECTRICAL SHOCK MAY BE RECEIVED. DO NOT PIERCE.
   Remove valve cover (6582). Refer to Section 03-01D .
   

1. Disconnect glow plug electrical connector using a pair of pliers.
   

1. Remove glow plug using 10mm socket.
   

1. Clean and inspect glow plug tip for damage. Replace if damaged.
   

Installation

1. Install glow plug and tighten to 19 Nm (14 lb-ft).
   

1. Connect glow plug electrical connector. Make sure glow plug wiring is routed to avoid moving parts.
   

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Glow Plug Control Glow plugs are used to warm the cylinders to improve cold-engine starting. The PCM uses the engine oil temperature (EOT) sensor and barometric pressure (BARO) sensor to determine how long the glow plugs will be on. The PCM energizes the glow plugs longer if the engine is very cold or if the barometric pressure is low at high altitudes.
The PCM controls the relay that supplies power to the glow plugs with the glow plug control (GPC) signal. When the GPC signal is grounded by the PCM the relay closes, turning the glow plugs on.
The glow plugs are controlled by the following sequence:

1. PCM energizes the glow plugs.

1. The PCM energizes the glow plugs immediately after the ignition is placed in the ON position.

1. The PCM then determines how long glow plugs will be on based on EOT sensor and the BARO sensor. The required time to warm up the cylinder decreases the engine oil temperature and barometric pressure increases at low altitudes.

Glow Plug Lamp Control The glow plug lamp (GPL) signal controls the WAIT TO START light located on the instrument panel. This light is used to indicate when to start the engine. The cylinders are being warmed by the glow plugs during and after this light is lit. The PCM energizes the glow plug lamp longer if the engine is very cold or if the barometric pressure is low.
When the GPL signal is brought low, the "Wait to Start" lamp is turned on.
The glow plug lamp is controlled by the following sequence:

1. PCM lights the WAIT TO START light after a key on reset occurs.

The PCM determines the glow plug lamp activation time based on engine oil temperature, barometric pressure and battery voltage.

1. PCM turns off the WAIT TO START light.

The glow plug lamp is turned off when the timer counts to the number of seconds specified by the PCM. The glow plugs will normally remain on longer than the "Wait to Start" lamp.
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Hello,
Your 94' F250 must have a 7.3 I'm sure. Is your engine a factory 7.3 powerstoke or a normally asperated diesel? The solenoid pack for the glow plugs has been a real common culprit for these Ford diesels. The following is most likely your problem.
1-bad ground or poor ground at the glow plug solenoid.
2-Defective solenoid for the glow plug circuit.
3-Defective glow plug in the circuit.

Ok to check these problems you can do the following.
Check the ground by taking a DVOM and checking the resistance between the engine or chassis ground and the mounting bolts that secure the solenoid to the engine.
Then check for a min of 11.8 volts to the solenoid input post. Then check the output voltage to I believe the brown ouput wire to the glow plugs. Check the connection furthest from the sloenoid typicly at cyl. 1 and cyl 5. This takes two pepole. Have someone else cycle the key while you check the voltage. If the voltage is good but still the solenoid is cycling off too quickly disconnect the brown output wire to the glow plugs and cycle the key again. If the problem goes away test each glow plug's resistance for a direct short to ground or the wire arness. If the problem persists I suggest replacing the solenoid.

turn key on and wait for the little curly light to go out then start it (glow plug light )looks like a coiled wire......