grounding
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Mountain Pass
Joined: Nov 2005
Posts: 206
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From: Baltimore,Md.
grounding
My 01 F-550 has a possible ground / start problem. I was wondering if anyone could tell me where the intake heater picks its ground up?? I have a new wire harness on the top of the engine and the truck will not start. I checked the glow plugs and relay out and it all checks out. when I test the intake heater relay out the ground wire on the relay is hot and the main wire to the heater is not and I'm assuming it's because the heater relay is not grounding. and when I take the ground wire off the relay it is working like it should
Also can I use a computer out of a 2000 truck with same features or is it truck specific
Also can I use a computer out of a 2000 truck with same features or is it truck specific
Posting Guru
Joined: May 2006
Posts: 2,274
Likes: 1
From: Milroy, PA
I am pretty certain that the PCM "grounds" that side of the relay coil. Power is always supplied to the coil, and when the pcm "grouds" the other side, current flows through and actuates the solenoid. The intake air heater has requirements, and is not necesarily on when the glow plugs are on. To check the intake air heater, you would be best of having two people, one to turn on the key, while you watch the multimeter. I cannot remember when/how long the intake heater works, but alot of people remove them without any trouble, even in the cold. I dont have mine hooked up anymore. Can you give us a little more detail as to whats going on? Ran yesterday, today wont start? Cranks fast, still doesnt start? cranks slow, etc? What led up to were you are sitting now?
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Mountain Pass
Joined: Nov 2005
Posts: 206
Likes: 0
From: Baltimore,Md.
This has been an ongoing problem for this truck. I went out to the truck and couldn't get it started. Had it towed to my shop and the engine would crank over fine with no problem but won't start. I checked all the glow plugs and replaced them. The truck still would not start on it's own. I can plug it in and the truck will start. Checked all the injectors and they check out as well. When I do get the truck started without plugging it in I get no throttle response until the engine is warmed. But if I plug it in I get throttle response because it is already warmed up.
Posting Guru
Joined: May 2006
Posts: 2,274
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From: Milroy, PA
Unfortunately I know you said you checked the glow plug relay, but I have this feeling its not working up to what it should. And the reason I think this, is because you say it wont start unless its plugged in, or warm. If you can, next time its cold (if its not already) take a decent size screw driver, and put it accross the two LARGE terminals on the glow plug relay. It will spark, dont be afraid, hold it there for about 15-20 seconds, and I bet your truck starts. Throttle responce for the first bit, while the truck is cold, is very very minimal, and the truck should not be driven hard, untill it is warmed up some. Typical diesel, and well any motor rules. (some just choose not to follow them) Another thing you can do to help, is run 5w-40 synthetic oil. It makes a pretty big difference in the cold.
But first things first, jump the two LARGE terminals on the glow plug relay, for 15-20 seconds, and then try to fire it up, and let us know what you find. There is a better, cheaper alternative to what ford sells for a gpr. Stancor model 586-902, which can be had from mouser.com.
But first things first, jump the two LARGE terminals on the glow plug relay, for 15-20 seconds, and then try to fire it up, and let us know what you find. There is a better, cheaper alternative to what ford sells for a gpr. Stancor model 586-902, which can be had from mouser.com.
Posting Guru
Joined: May 2006
Posts: 2,274
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From: Milroy, PA
You say you "checked" the glow plugs, and relay. How did you "check" the glow plugs? Make sure the connector was on them or pull them out and visually inspect them?
Another thing you can look at, is to take the top screw off the HPOP resovior, and see what the level is before start. The oil level shouldnt be any more then about an inch from the top. A flashlight can help.
As far as the pcm goes, a 2000 should be ok with a 2001. I THINK. If it came out of an auto truck, and yours is an auto, or if yours is a stick, and it was a stick. There should be a code on the pcm, and one on yours and if they match then it will work (assuming they both had the same tranny) However, I would not switch out a pcm in hopes of fixing your problem.
Another thing you can look at, is to take the top screw off the HPOP resovior, and see what the level is before start. The oil level shouldnt be any more then about an inch from the top. A flashlight can help.
As far as the pcm goes, a 2000 should be ok with a 2001. I THINK. If it came out of an auto truck, and yours is an auto, or if yours is a stick, and it was a stick. There should be a code on the pcm, and one on yours and if they match then it will work (assuming they both had the same tranny) However, I would not switch out a pcm in hopes of fixing your problem.
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Mountain Pass
Joined: Nov 2005
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From: Baltimore,Md.
I did both. Pulled the plugs out and ohm tested. All is ok. I also checked the HPOP res and it is within specs.
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Posting Guru
Joined: May 2006
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From: Milroy, PA
What is your battery voltage (measured with meter, not the gauge) before you turn the key on, and when you first initally turn the key on (glow plugs should be on), and once they turn off? IE key off should be around 12.4, key on, glow plugs on, in the 10.8-11.4 range, then once they turn off it typically will creep up to aroudn 12 volts again. what do you experience?
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Mountain Pass
Joined: Nov 2005
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From: Baltimore,Md.
with the key off I am getting 12.5 and with key on it is 11.4 and I notice that when the wait to start light goes out the voltage does not change . Like the relay is not cycling off and on
Posting Guru
Joined: May 2006
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From: Milroy, PA
Good info! With the meter again, one side on the battery ground, check the voltage at both large terminals of the glow plug relay. Key off. Let me know what you find.
EDIT: Just in case, the glow plug relay is the one closest to the firewall. The front is the Air Intake Heater relay. Although I think you know that.
Also, good batteries and warm temps (50+ F) can make the voltage stay up above 11, while the glow plugs are on. And just because the wait to start light is out, does not mean the glow plugs are off. After the light goes out, wait another 20 seconds or so and check battery voltage one last time.
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Mountain Pass
Joined: Nov 2005
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From: Baltimore,Md.
ok what I got was 12.5 with key off on battery side and 0 on glow plug side. Turned the key on and got 11.4 volts. Then it took 45 seconds and then the voltage did drop off of the glow plug side and then the battery side was back to 12.5 volts
Posting Guru
Joined: May 2006
Posts: 2,274
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From: Milroy, PA
Well that tells me your glow plug system is infact working. I am at a little bit of a loss at this point. This isnt really a fix, but about the only other thing I would want to do, is run 5w-40 synthetic, but at 50 degrees (what its been here in the morning) its not really a requirement. These trucks will start down to zero on regular oil, it just takes more glow plug cycles usually. I guess without actually looking at the truck, Im not sure I can offer any other advise.
One last thing to try, cycle the glow plugs three times (watching the wait to start light) when it goes out, turn off the key, and turn it back on (cycling) and see if it starts after the third try.
One last thing to try, cycle the glow plugs three times (watching the wait to start light) when it goes out, turn off the key, and turn it back on (cycling) and see if it starts after the third try.
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Mountain Pass
Joined: Nov 2005
Posts: 206
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From: Baltimore,Md.
well been there done that too rebel. I'm at a loss as well. That's why I said it doesn't make sense that I can plug the truck in and when the block/coolant warms up the truck starts. I even called a friend at the sealership and they could only tell me that maybe the glow plugs themselves are in fact not working. So I'm pulling a valve cover off to see if in fact the glow plugs are working or not.
Elder User
Joined: Mar 2003
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From: northern Michigan
Sounds like either a bad glow plug relay or you have an issue with the wiring harness connectors at the valve covers that are preventing the glow plugs from getting power. Plugging in the block heater and it starts after a bit indicates the glow plugs are not working.
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Mountain Pass
Joined: Nov 2005
Posts: 206
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From: Baltimore,Md.
well it appears the glow plugs are in fact working. I pulled the valve covers and the glow plugs. I put the glow plugs one by one on the connectors and turned the key on momentarily the check glow plugs and they are in fact getting hot