Question about 2006 Ford F-250 Super Duty

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Where is the glow plug relay and how do I check it to see if its the cause of ongoing battery drain?

I have continued battery drain - key off - that is not due to the alternator or any identifiable fuses or relays so far. I suspect the glow plug relay. Where is it located and how do I get to it and how do I check to see if thats the problem?

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  • djones5173 Oct 25, 2008

    6.0 L 2006 F250 diesel



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Is the engine a 6.0l or a 6.4l

Posted on Oct 25, 2008

  • Anthony DiVeronica Oct 25, 2008

    The Glow plug relay on a 6.0l is located in one of two places. On the driver-side rear of the engine on the valve cover or the passenger-side front of the engine on the valve cover. It is an aluminum rectangle with two plugs that go into it one green and one black or gray. To check for a parasitic-drain do the following: if the truck had dual batteries disconnect one of them completely (+ and - terminals) next take the remaining battery and remove the positive cable. Now take a multi-meter w/alligator clips and clip the black lead to the positive cable on the truck, now clip the red lead to the positive battery terminal. Set your meter to Amps DC, with key key off for at least 1 min and no accessories on (radio, lights, etc...) your reading should be less than .3 amps. if you have a reading more than that then your battery will go dead over time. To check your glow plug relay simply unplug it and watch your reading on the meter.



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Why will car not start from key? Just turns over until battery drained, seems too sluggish to start

Has the fuel pressure been tested? Are you sure the ignition starter switch is ok and doesn't have an open that causes a stall out when the key is released. We do not have the diesel engine in this country so repair info is limited. You need to stop guessing and consult an expert, you have replaced parts that I would never replace for this kind of issue, a total waste of money and your time.

Oct 01, 2016 | 2003 Ford Focus

1 Answer


You obviously have something stuck "on" draining the battery. Check the glow plug relay to make sure there is no power coming out of it unless it is in a heating cycle. Also, check interior lights, glove box light, trunk light, etc. to make sure they are shutting off as they should.

Feb 25, 2014 | Volkswagen Beetle Cars & Trucks

2 Answers

Will bump start but not off key

If the car turns over you can crank the engine using the key and it turns over fast, but it won't start, could be down to low fuel pressure, possibly fuel pump. Could be the coil ( which I doubt as the car starts when bumped) or, like you say, the plugs. The fact that the engine fires up when pushed, and the lack of info regarding how well the engine turns over using the battery, seems to me that it could be either a bad earth ground from the battery, but more likely a bad battery that's lost it amps and losing its charge quickly when the engine is off. Engines can turn over with a bad battery but the amps are bad and it dies quick. One thing you could try would be to see if you can get someone to jump start the engine using cables. If the engine starts its most likely the battery. You may still encounter a problem using cables because there still might not be enough amps getting through, so the best option would be to try a different battery first. Your car is starting when bumped which makes me think the plugs are ok, as when power reaches the plugs, they heat up and create combustion. If the fuel pressure is low, this could cause your problem, as the bump will increase the pressure and supply allowing it to start. I'm not sure if your car is electronic pump or mechanical. If it's electrical this could be unlikely the cause unless the power drain when trying to crank the engine from the battery is causing poor fuel supply from the electric pump. There is another you allow enough time for the glow plugs to heat up? some cars as they age prefer some time with the key on to the point the dash lights are on, and wait 30 seconds and then turn over the engine, this power supply can allow the plugs to heat up prior to being turned over. One other thing could be the pre- heaters. I'm not sure the exact names, but modern engines have a system that pre-heats the plugs, like pre-coils or something. This could be bad.

Try this first:
turn key to the point the ignition is on fully with lights on but don't turn over the engine. Leave it 30 seconds and then turn over the engine. See if this works. This will help heat the plugs and prime the fuel pump.

If this does not work, then try to get someone to jump start your car using cables. Again follow the previous tip. If this works it's likely your battery.

If this does not work, try a different battery. hopefully someone can loan you one. If this works, it's your old battery. some batteries are maintenance free, so you shouldn't top up with distilled water, but some are not and lose water. If it's low, top it up with distilled water. Do not use tap water. Be careful handling the battery with the caps off. Do not over fill.

If this does not work, try new glow plugs.

If this does not work, it could be the fuel pump causing low pressure.

Lastly, when you key the engine to turn it ove, does it just click? If you just hear a click from the starter motor, then either the battery is bad, a bad earth ground requiring a clean of the terminals and reconnecting them, or new starter motor. If you just hear a click and the battery is good, see if you can get someone to whack the starter motor body with a hammer and it may start. Be very careful not to have the car is gear, to no get your hand caught in moving parts, etc. This is at your own risk, please google how to do this and then decide if you wish to try.

There can only be so many problems. Power or fuel. It starts when pushed, so it gets fuel from the pump when pushed. The plugs get power when pushed. The key is does it turn over from battery, and is it getting enough amps. Good luck

Nov 06, 2013 | Peugeot Cars & Trucks

1 Answer

Hyundai Accent 1.5 Diesel. Intermittent problem with starting. Sometimes starts and runs fine. However sometimes on starting car will not run above 750 rpm and throws out HUGE clouds of black smoke. ...

it sounds like a glow plug issue. perhaps a bad glow plug relay. I would think its the relay if the problem comes and goes. If it were a bad glow plug the problem would be constant. check for volts at the glow plugs next time the car acts up. If you find no volts, tap on the glow plug relay next time you turn the key on. This may cause it to activate. if so then replace relay

Jan 05, 2011 | 2003 Hyundai Accent

1 Answer

My 2003 Renault Megane Scenic 1.9dci expression won't start

The funny sound you mentioned must be identified, could it be the starter trying badly to turn. Here the fault of your battery drain is that the glow plugs take a lot of current and it must NOT come ON when the starter motor runs. Hence the fault could be your GLOW plug relay unit with the auto cut off timer that is faulty. If you keep draining the battery to a lower threshold level , there is every possiblity that the battery life will be lowered . I hope the present battery rating is the recommended Amp/hr rating to give the extra run for the morning start. Next area of suspicion is the starter motor itself , it could have a bad commutator or a bush. It will be good to have a clean up and service. Finally check for excessive drain on your battery with a current check in series for the drain current when the switch if off. If the current exceeds the limit disconnect each circuit to confirm. hope this advice helps. good day

Jul 22, 2010 | 2003 Renault Sportwagon

2 Answers

Glow plugs stopped working on a pajero 2.8td 1994 model, plugs and buzz bar are ok.

My glow rail would come on for a very short time, then turn off (less than 1 second).
Replaced the control wire for the glow relay, with a test lead from battery to relay control terminal - relay was working fine (relay is between batteries).

Checked the engine temperature sensor (located on top of the housing where the top radiator hose attaches to the engine).
Take out and test in a pot of water (need a 19mm deep socket to remove).
At 0 deg C should be 8.6K ohms
At 20 deg C should be 3.25K ohms
At 40 deg C should be 1.5 K ohms
At 80 deg C should be 300 ohms
I replaced the temperature sensor with a 8.2K ohm resistor (engine cold).
Then tried with a 1.2K ohm resistor (engine hot).
Each time I tested the glow rail at the relay (with a multimeter) it would turn off after about 12-14 seconds, which is normal, to protect the glow plugs and battery drain (they come on again when engine is starting).

When I put the temperature sensor back in, the glow rail was working fine again - only thing I can think of is that the contact between the sensor and the plug, may have had a oxide formed and caused a high resistance or open circuit, indicating to the glow controller that the engine was hot and did not need glow activation.
So try taking the plug off the temperature sensor, and reattaching it again it might be all it needs, to clean its contacts.

Feb 01, 2010 | 1994 Mitsubishi Montero

1 Answer

Glow plugs causing starting problem

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.
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.

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.

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.
Glow Plug Removal
    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.
  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.
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.

Mar 14, 2009 | 2004 Ford F350

1 Answer

2000 tdi wont start!!!

glow plug relay is marked #180 on the housing.
in 0 to 11 degrees they have a starting prob were the glow plugs go on and off very quickly.need to exstend glow plug timing.
to test glow plugs disconeect ect turn key on plugs should draw 15 amps each 60 amps all together.if you dont have amp meter use test light.

Nov 24, 2008 | 2000 Volkswagen Jetta TDI

1 Answer

Fuel Pump Runs Continuously - Not Relay

It could be some water in a wiring harness plug causing the relay to stay on constantly, or a short to earth in the switching side of the fuel pump circuit, but really it needs a auto electrician to have a look over it to find out why the relay is staying powered on all the time. When you plug in the relay can you feel it click on straight away? Or does the pump run regardless of whether the relay is plugged in or not? If the latter is true, check for damage to the wiring loom from the relay to the pump. Other than that, its probably auto sparky time.

Hope this helps,

Nov 02, 2008 | 1997 Ford Contour

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