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California emissions LB7. Code P0380 won’t go away. I’ve replaced all the glow plugs and the glow plug controller. I checked the 175A glow plug fuse and it’s good. What now?! I’m stumped. Anything I can do just so I can get my registration tags. Damn SES light screwing up everything.

Please help
 

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Wiring or IAH

California emissions LB7. Code P0380 won’t go away. I’ve replaced all the glow plugs and the glow plug controller. I checked the 175A glow plug fuse and it’s good. What now?! I’m stumped. Anything I can do just so I can get my registration tags. Damn SES light screwing up everything.

Please help
If the controller has been replaced with the glow plugs, that leaves wiring, or intake air heater.

I had a bad wire on mine that the previous owner had replaced with a crappy crimp connector that corroded.

I simply used a DMM with one side on ground, the other going to each pin in the glowplug controller connector. I found one that changed when you wiggle the harness. Traced the wire, found problem.

AlldataDIY.com subscription can tell you which wires are which. It even explains the voltages for the signal wire that tells the ECU what the problem is, means. Specifically, how many plugs are reading as bad.
There are also tons of diagrams regarding the circuit that explains how everything works. At $10/year, I highly recommend it.


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DTC P0380 (CALIFORNIA WITH RPO CODE YF5, NE1)

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. The California Glow Plug system has eight individual glow plug supply circuits between the controller and the glow plugs. If the feedback voltage from the controller to the ECM is not within range, DTC P0380 will set.

CONDITIONS FOR RUNNING THE DTC
The ignition is ON.

CONDITIONS FOR SETTING THE DTC
The glow plugs are commanded OFF and the glow plug feedback is more than 2 volts.

or

The glow plugs are commanded on and the glow plug feedback is not between 5 volts and 6.2 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.

IMPORTANT: If the glow plug relay is stuck in the ON position, check for proper operation of the glow plugs. When the glow plugs are commanded ON by the scan tool, an internal engine control module (ECM) timer protects the glow plugs from damage by cycling them ON for 3 seconds and the OFF for 12 seconds . The glow plug relay battery feed wire nut at the relay should be tested for proper torque. The California glow plug system will send the following voltages, or signals to the ECM:
 

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California emissions LB7. Code P0380 won’t go away. I’ve replaced all the glow plugs and the glow plug controller. I checked the 175A glow plug fuse and it’s good. What now?! I’m stumped. Anything I can do just so I can get my registration tags. Damn SES light screwing up everything.

Please help
Aside form my prior post, to answer your direct question here:

Technically, if you were to disconnect/cut the single sense wire that feeds your ECU the reporting from the glow plug controller, a 5-6v signal, the ECU will think the glowplug controller is reporting all is good, none of the glowplugs are malfunctioning.

I sure would fix the problem correctly, but as someone who has had to drive with expired tags in Cali due to smog crap, I thought I would add that temporary measure as an option.
 

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“The California Glow Plug system has eight individual glow plug supply circuits between the controller and the glow plugs.”

My ‘03 CA, has a bus connecting the four glow plugs on each side. They are in parallel.

Just wanted to confuse things.
 

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“The California Glow Plug system has eight individual glow plug supply circuits between the controller and the glow plugs.”

My ‘03 CA, has a bus connecting the four glow plugs on each side. They are in parallel.

Just wanted to confuse things.
I have seen North Eastern vehicles with egr and the glow plugs bus, but not a true Cali one with bus. So many variants though, it doesn't surprise me.
 

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I had the same issue. This YouTube Video is pretty helpful with the diagnostic procedure. He gives all the necessary pin numbers and wire colors.


Hope this helps.
 
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