Glow plug relay question
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Glow plug relay question
I have replaced the glow plugs twice in the last 1 1/2 years on my '97 F250 and now they apparantly need it again!! Any ideas on what is making them burn out so fast? The original ones lasted 125,000 - now this!
I changed the glow plug relay - it didn't help. As I was poking around, I noticed a wire from the glow plug relay goes to a 2nd relay on the passenger side fender. I never see this relay (or whatever it is) mentioned here. Anyone know what it is, how to test it, part # etc. I am thinking if it is some kind of timer and it is keeping my plugs on all the time, then this would explain the untimely death of my plugs - but that is just a guess.
Any help would be appreciated, as I am sick of changing these plugs and sick of a non-starting truck when it isn't even cold!
I changed the glow plug relay - it didn't help. As I was poking around, I noticed a wire from the glow plug relay goes to a 2nd relay on the passenger side fender. I never see this relay (or whatever it is) mentioned here. Anyone know what it is, how to test it, part # etc. I am thinking if it is some kind of timer and it is keeping my plugs on all the time, then this would explain the untimely death of my plugs - but that is just a guess.
Any help would be appreciated, as I am sick of changing these plugs and sick of a non-starting truck when it isn't even cold!
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Joined: Nov 2000
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From: Cincinnati, Ohio
What brand of glow plugs did you put in? That may make a difference.
The relay you refer to on the fender is the starter relay. The wire running from that to the glow plug relay is simply a constant hot power source for the glow plug relay to use.
With key off you should have battery voltage to one large terminal and nothing to the other large or either of the small terminals.
With key on for the first two minutes or so you should have battery voltage to both large and one small terminal. The other small terminal should show ground. This shows the relay active.
With the key on and after the glow plug cycle has finished you should have battery voltage to one large and both small terminals. The computer activates the relay by grounding the second small terminal thus activating the relay.
It is possible to have battery voltage to both large terminals when the relay is active and still have a bad relay. If the contacts inside are pitted or corroded you may have low amp voltage passing through it but not enough power to actually run the glow plugs.
Click HERE to go to an excellent article on the glow plug system. It is from a few years back. I have an MS Word document saved with those instructions updated in a couple minor ways and the originating post of my thread when I replaced the glow plugs on my truck a while back. If you would like a copy send me an eMail through this site with GLOW PLUG INFORMATION in the subject line and the eMail address you would like me to use and I will reply with an attachment. Do not send a PM - they will not work for an eMail address.
Dave / Believer45
The relay you refer to on the fender is the starter relay. The wire running from that to the glow plug relay is simply a constant hot power source for the glow plug relay to use.
With key off you should have battery voltage to one large terminal and nothing to the other large or either of the small terminals.
With key on for the first two minutes or so you should have battery voltage to both large and one small terminal. The other small terminal should show ground. This shows the relay active.
With the key on and after the glow plug cycle has finished you should have battery voltage to one large and both small terminals. The computer activates the relay by grounding the second small terminal thus activating the relay.
It is possible to have battery voltage to both large terminals when the relay is active and still have a bad relay. If the contacts inside are pitted or corroded you may have low amp voltage passing through it but not enough power to actually run the glow plugs.
Click HERE to go to an excellent article on the glow plug system. It is from a few years back. I have an MS Word document saved with those instructions updated in a couple minor ways and the originating post of my thread when I replaced the glow plugs on my truck a while back. If you would like a copy send me an eMail through this site with GLOW PLUG INFORMATION in the subject line and the eMail address you would like me to use and I will reply with an attachment. Do not send a PM - they will not work for an eMail address.
Dave / Believer45
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Thank you for the info on checking the relay. I now have 3 of them and am not certain if they are all good, all bad or some combo thereof. Now I can go check them.
I had thought of the constant power from the starter relay as a possibility, but figured it best to ask the experts...
As far as glow plug brand - I used the Beru plug the first time (they lasted about a year (20k) then I used plugs from NAPA the 2nd time - don't think I've got 10k on them - very frustrating.
I had thought of the constant power from the starter relay as a possibility, but figured it best to ask the experts...
As far as glow plug brand - I used the Beru plug the first time (they lasted about a year (20k) then I used plugs from NAPA the 2nd time - don't think I've got 10k on them - very frustrating.
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From: Cincinnati, Ohio
Mbpulaski, that rather stinks. I have a set of Beru I got at AutoZone a little over three years ago that have been fine - they came in Ford part bags with the Ford part number on them. Last year I never did plug the truck in (I linve in Cincinnati - not exactly winter wonderland but it gets to zero and below sometimes) either at home or at work. I do not know what brand NAPA sells but I would suggest the Beru again. Where do you live and how cold does it get?
I have not run across glow plug failure like this before - hopefully the "luck of the draw" with the NAPA plugs.
Dave / Believer45
I have not run across glow plug failure like this before - hopefully the "luck of the draw" with the NAPA plugs.
Dave / Believer45
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Originally Posted by believer45
Mbpulaski, that rather stinks. I have a set of Beru I got at AutoZone a little over three years ago that have been fine - they came in Ford part bags with the Ford part number on them. Last year I never did plug the truck in (I linve in Cincinnati - not exactly winter wonderland but it gets to zero and below sometimes) either at home or at work. I do not know what brand NAPA sells but I would suggest the Beru again. Where do you live and how cold does it get?
I have not run across glow plug failure like this before - hopefully the "luck of the draw" with the NAPA plugs.
Dave / Believer45
I have not run across glow plug failure like this before - hopefully the "luck of the draw" with the NAPA plugs.
Dave / Believer45
With the plugs I have now, the truck starts really, really hard even at 60F. If I plug it in for 1 1/2 hrs, starts right up.
Just a frustrating deal. I want to sell this one when my new '05 comes in, but I am kinda obligated to fix the glow plugs AGAIN first.
