Glow plug relay check
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Lead Driver
Joined: Apr 2003
Posts: 9,965
Likes: 1
From: H-town, MN
Glow plug relay check
How do you test the glow plug relay? My '99 is hard to start and I am thinking it is the relay, not sure though. I replaced glow plugs due to hard start and still not it. They were getting weak anyway. If I plug it in it (in my garage at 40*) it will start right up. If not, it will not start till many cranks and alot of swearing. I read up on jumping the two big terminals for around 30sec and then try starting. I will have to try that after I get off of work. My truck is at the tranny shop right now (bad leak, maybe fried) but I still have access to it. Any input would be great. Truck has 205,000 miles and the little things are starting to go (expected). 
Logistics Pro
Joined: Aug 2005
Posts: 3,886
Likes: 180
From: Morgan Hill, CA
The easiest way is to just monitor the system voltage for a min or two at startup. The voltage will jump as soon as the GP's turn off. You can see it on a voltmeter, or just watch the interior or headlights and you'll see them suddenly get much brighter when they kick off. The light method works best at night...
Post Fiend
Joined: Feb 2006
Posts: 11,892
Likes: 2
From: Middle Tennessee
Take a multimeter lead from the terminal opposite the one direct wired to the battery, and ground the other lead to the block or preferably the negative battery terminal. Key out reads nothing. When cold and key to WTS, it should read battery voltage and that should be 10.5 or well above. If not, your GPR is letting you down.
