GPR post gets hot

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Mar 27, 2006 | 02:10 PM

sc93f

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Joined: Oct 2003

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From: Commerce Twp, MI

GPR post gets hot

Looked through the GPR sticky, didn't see anything like this. I could have missed it. Today when I cycled the key on to check for some other things, I started smelling plastic burning. Turns out to be the GPR post is getting very hot when it is cycled on, the side connected to the battery. Has anyone encountered this? Probably time to just replace it. Truck has 90k miles. Measured voltage across it, got between 9-10 V on the glow plug side with 12.5 V on the battery side.

Mar 27, 2006 | 02:13 PM

PSNut

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From: New Hampshire

Quote:

Originally Posted by sc93f

I had that same thing happen...that's what happens when the contacts become more resistive from carbon buildup. Resistance =heat. Replace the GPR and thoroughly clean the terminals.
Nut

Mar 27, 2006 | 03:10 PM

lukecline

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From: minneapolis, ks

i would check connections and try cleaning terminals and wire ends before replacing. Like psnut said, its probably loose connection or corrosion.

luke

Mar 27, 2006 | 05:17 PM

sc93f

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From: Commerce Twp, MI

Thanks guys, I'll try cleaning it up.

Mar 29, 2006 | 01:50 PM

sc93f

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From: Commerce Twp, MI

Also, I checked the resistance of my glow plugs this weekend, and all of mine ohmed out at 0.5, less than the specs I've seen written here. This means at 12V, the glow plugs are drawing 3 amps through the relay. However, with my measured 10V on the output side, this would be 2.5 amps through the relay. Now, I have 2.5 V drop across the relay, at 2.5 amps, means my relay currently acts like a 1 ohm resistor.

Could my low resistance glow plugs be causing damage to the relay by drawing more amperage? Thought I saw somewhere they were only rated for 1 amp.

Mar 29, 2006 | 02:25 PM

guzzle92

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Joined: Feb 2005

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From: Northern Colorado

Quote:

Originally Posted by sc93f

Could my low resistance glow plugs be causing damage to the relay by drawing more amperage? Thought I saw somewhere they were only rated for 1 amp.

Like nut said, the additional current and voltage drop is being caused by carbon buildup on the internal relay contact. Every time the GPR cycles, the contact arcs. Eventually the carbon depost left from this arcing will lead to increased resistance which causes the additional current draw. Replace the GPR with a inexpensive one from NAPA (109?) and your heat problem will go away.