how do you test the glowplug relay
 

Ok Guys, I got code PO380 glow plugs, How do I test the relay for the glow plugs, how can I test the glowplugs too. thanks

To test the GP relay, you can use a test light. Just find a good ground and test the switched side as someone cycles the ignition. If it goes on and off again ok.

To test the glow plugs, you can use an Ohmmeter to check the resistance between the terminals. Anything 5 or less is ok, if you get no reading then it's toast.

Also make sure the buss bar (if you have Federal emissions LB7) is not corroded or rusty as this could effect operation.

Ok from what I gather the glowplug relay is behind the driverside valve cover in the black little box with two connectors pluged into it is that it? do I unplug the connectors and take the box out or am I looking at the wrong part here? Thanks

That's it. you can test the terminals coming off the relay or check for power at the bus bar.

is it a federal or cali emmisons truck, if its a cali it will most likely be the glow plugs. if its a fedral it will most likely be the controller.

The Federal has the glow plugs connected together with the black bar going across all 4 on each side.

let us know so i can post more info :U:

I don't have any power on my bar. It must be federal, it has the solid black bar across the gp. how do it get the relay out of there. Do I just unplug the two connectors or is there some more wires to unplug on her. Thanks for all the help Guys. Later :c:

There i two wires you need to unbolt, one that goes to the intake air heater an the 12v supply to the relay. the rest the two pink wires and 4 wire connector can be undone at the connectors.

there is two 13mm nuts holding down the relay IIRC and they easily accessable. it also helps to undo the wire going down to the glow plug from the relay before unbolting it.

CIRCUIT DESCRIPTION
The glow plug system is used to assist in providing the heat required to begin combustion during cold engine temperatures. The glow plugs are heated before and during cranking, as well as initial engine operation. The engine control module (ECM) controls the glow plug ON times by monitoring coolant temperature and glow plug voltage.

CONDITIONS FOR RUNNING THE DTC
The ignition switch in the ON position.

CONDITIONS FOR SETTING THE DTC

• The ECM has commanded glow plugs ON and the glow plug signal voltage is less than 4 volts .

or

• The ECM has commanded glow plugs OFF and the glow plug signal voltage is more than 4 volts .

ACTION TAKEN WHEN THE DTC SETS

• The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
• The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

CONDITIONS FOR CLEARING THE MIL/DTC

• The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
• A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
• A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
• Clear the MIL and the DTC with a scan tool.

DIAGNOSTIC AIDS
If the glow plug relay is stuck in the ON position, check for proper operation of the glow plugs, refer to Glow Plug System Diagnosis. When glow plugs are commanded ON by the scan tool, an internal ECM timer protects the glow plugs from damage by cycling them ON for 3 seconds and then OFF for 12 seconds . See: Component Tests and General Diagnostics\Glow Plug System Diagnosis

The glow plug output feed wire nut and battery feed wire nut at the relay should be checked for proper torque, 5 N.m (44 lb in) and for corrosion.

An intermittent may be caused by the following:

• Poor connections
• Rubbed through wire insulation
• Broken wire inside the insulation

TEST DESCRIPTION

https://www.dieselbombers.com/attach...1&d=1254453433
https://www.dieselbombers.com/attach...1&d=1254453601
https://www.dieselbombers.com/attach...1&d=1254453601

for some reason i cant get the other two pages big :argh:

most likely its the relay though

OK. I will try to get that relay out of there. Where is the best place to get one? Dealer or a parts store? Thanks for the help, Later