Glow plug relay issue

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Jan 18, 2018 | 08:22 PM

64highboy

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Senior User

Joined: Nov 2011

Posts: 167

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From: Vancouver island

Glow plug relay issue

I replaced a glow relay a couple months back and the last couple days my truck has had hard starting so I checked the relay again and it isn’t getting power at the one big terminal wii the key on. The terminal that comes from the battery has power. The two small terminals also have power when the ignition is on. I put a test light across the two big terminals and it lights up so this must mean there is a short inside the relay perhaps? I also read crappy batteries can cause this to I’ve noticed my factory voltmeter seems to read lower than it used to from what I can remember. Alternator packed it in a few months ago so I replaced that but the batteries are about 5 or six years old they are Costco batteries and they say in another truck of mine for a couple years and never hot used however they have been in my current truck 3 years. Can anyone chime in with suggestions or maybe someone has encountered a similar problem. The relay was a Napa

Jan 18, 2018 | 08:41 PM

Red97350

Laughing Gas

Joined: Oct 2009

Posts: 882

Likes: 11

From: Eastern CT

The PCM will ground out one of the trigger wires for the GPR. Since the test light lights up when you put it across the two large terminals of the GPR, it only means that the GPR is not closing.

Red

Jan 18, 2018 | 08:45 PM

madpogue

Lead Driver

Joined: Oct 2003

Posts: 8,476

Likes: 37

From: Madison, WI

No point in testing for voltage at the small terminal that goes to the PCM. As said, it's the coil circuit ground, so check for continuity between that terminal and ground when the key is first turned to RUN. If that's good, the PCM is working, and most likely the relay has already failed. Skip the FLAPS cr@p, get a Stancor / White-Rodgers 586-902 or Western Plow 56131-K.