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Glow plugs, 87 thru 94, new style system

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Old 08-04-2009, 09:44 PM
waldrop4 waldrop4 is offline
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Glow plugs, 87 thru 94, new style system

Hey guys, I need some help on my glow plug solenoid. The two hot leads from the starter solenoid are 13v to the post on the glow plug solenoid. When the key is on I am only reading 5 to 7 volts on the opisite post that goes to the glow plug harness. What should it read? What does this indicate? Note that before starting failure it was hard to start. Took 5 seconds to start or more. I would appreciate any help Don
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Old 08-05-2009, 09:22 PM
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waldrop4,
Welcome to FTE and the IDI diesel forum.

Voltage drop will have the voltage on the glow plug side of the relay lower when the glow plugs are heating.
200 amps through rather small AWG wire.

That said, there are two places you need to look.
First look at the chassis to engine connector, circled in red in this picture.



That picture is on a 6.9 engine, so your is a little different.
In the picture the large AWG wires, orange color will be either yellow or tan on yours.
There will be two, both on the same end of the connector, You connector will be either black or white if I remember right.
Anyway, look for signs the connector has been hot, deformed or burnt looking plastic.
If you see that, the connector terminals are not making a good connection.
The only fix is to splice the wires aroung the connector, very common problem.
Caution, the wires are always hot, direct connection to the battery positive post.

The other possibility is the relay contacts have burnt up.
The relay from an 86 6.9 engine will bolt right on top of your controller, just make sure you get all the wires back in the same locations.



1986 6.9 glow plug relay, about 30 dollars at NAPA.

Incase you don't see them, the small green controller wire is on the terminal at the end of the metal strip labeled GLOW PLUGS, the small yellow wire in under the other end of the strip on the large terminal of the relay opposite the battery terminal.
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Old 08-10-2009, 05:18 PM
waldrop4 waldrop4 is offline
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re: hard starting 7.3

I have bypassed the wires coming from the starter solenoid and wire nuted them together. I also replace the glow plug solenoid and checked my wires according to the diagram that Dave sent me. I did get it started but it took rolling it off a hill and popping the clutch. It would start right up after I drove it around easy. The next morning I went out to check it and it still wont start on its own. The glow plug light comes on then it starts cycling really fast. Is that normal. Or could it be the IP not doing its job? I kind of rulled that out because it wouldnt even start with a little squirt of either before I finally pushed it off a hill to start it. Thanks any help would be appreciated,
Don
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Old 08-10-2009, 10:12 PM
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How long does the glow plug light stay on solid for the first start of the day?

You should be looking at 8 or 10 seconds.

Start the engine as soon as the light goes out.
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Old 08-11-2009, 07:19 AM
waldrop4 waldrop4 is offline
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re: Dave

Dave, I tried this morning and the light stays on for 2 seconds then there is a clicking noise from the glow plug solenoid. It clicks about 2 times a second. I have referred to this as the glow plugs cycling. thanks for your reply
Don
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Old 08-11-2009, 08:21 PM
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Two seconds is the glow plug controller telling you that you have burnt out glow plugs.

If you don't start the engine, after the initial 10 seconds, the controller will cycle the glow plugs to keep the cylinders warm, which is normal.



Two methods to check glow plugs, ohms is a better test, but an automotive circuit tester is faster.

Fast test, clip the ground clip of a test light to the positive battery terminal.
Remove the first glow plug wire connector and touch the tip of the tester to the glow plug terminal.
If the tester lights, the glow plug is probably good.
If it does not light, the glow plug is bad.
Continue until you have checked all 8 glow plugs.


More accurate test if you have a fairly good ohm meter.
The glow plug resistance should be between .5 and 1 ohm when the engine is cold.
Check resistance between the threads and electrical connection.
This test can be done with the glow plug installed, touch the hex on the barrel with the probe that would be on the threads.

If you try this test with a cheap meter, the normal resistance is so close to a dead short, it will probably just show a short or 0 ohms.

The 87 thru 94 uses Motorcraft/Beru ZD 9 glow plugs.

Champion, Autolite, Wellman are all junk, don't use them.
Bosch I have heard more bad stories than good ones.
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Old 08-12-2009, 11:05 PM
waldrop4 waldrop4 is offline
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Hey Dave re:7.3 88mdl

Dave I installed two more glow plugs which made eight new ones. And guess what? The light stayed on 10 seconds and fired right up. You are ausome thanks a bunch. You taught this okie a few more tricks. God Bless, Don
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Old 08-13-2009, 09:39 PM
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Just glad you are back on the road.
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Old 11-08-2009, 12:47 AM
dyoungen dyoungen is offline
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Motorcraft/Beru for the glo plugs. I have an 87 F250 and couldn't find the controler. Come to find out I had the new system that bolts to the back of the engine behind the CDR which is behind the aircleaner. I don't know if the PO changed it or what but after changing the box it has worked fine. If you can't find the screw in controler you might have the new system which Dave has pictured as the second picture, the new controler complete with writing. I went to OReilly's and they only listed it as a 1990.
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Old 11-09-2009, 05:14 PM
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92 idi 7.3 glow plug prob

ok new here now on to my problem glow plug light comes on for 8-10sec light comes on with the clicking sound light goes out got power to gp selnoid no power to glow plugs any help will be appericated
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Old 11-09-2009, 09:02 PM
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tow pro 570,
Welcome to FTE and the IDI diesel forum.

The glow plug light on for 8 to 10 seconds is when the glow plugs are heating.
When the light goes out, no power to the glow plugs.

8 to 10 seconds sounds about right unless it is very cold where you are.
You should try to start as soon as the light goes out.

Does the engine start OK or are you having start problems?
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Old 11-10-2009, 09:53 AM
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truck won't start have no power out to the glow plugs, selnoid has power on ign side and battery side ,no power to glow plugs,light comes on click light goes out with out a click no power to glow plugs
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Old 11-10-2009, 08:35 PM
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Get a glow plug relay for an 86 F350 diesel, then change the relay on top of the controller.

Put the wires back on exactly like they are now.

Cost should be around 25 dollars.
If you get the one for your 92, it will probably be a complete controller/relay and cost over 100 dollars.

I would guess the contacts have burnt in the relay you have now.
NAPA should have one in stock.

Make sure they don't give you a starter relay, they are different electrically and have a small I and S, one by each of the two small terminals.
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Old 11-17-2009, 04:48 PM
jedstamm jedstamm is offline
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Quote:
Originally Posted by Dave Sponaugle View Post
waldrop4,
Welcome to FTE and the IDI diesel forum.

Voltage drop will have the voltage on the glow plug side of the relay lower when the glow plugs are heating.
200 amps through rather small AWG wire.

That said, there are two places you need to look.
First look at the chassis to engine connector, circled in red in this picture.



That picture is on a 6.9 engine, so your is a little different.
In the picture the large AWG wires, orange color will be either yellow or tan on yours.
There will be two, both on the same end of the connector, You connector will be either black or white if I remember right.
Anyway, look for signs the connector has been hot, deformed or burnt looking plastic.
If you see that, the connector terminals are not making a good connection.
The only fix is to splice the wires aroung the connector, very common problem.
Caution, the wires are always hot, direct connection to the battery positive post.

The other possibility is the relay contacts have burnt up.
The relay from an 86 6.9 engine will bolt right on top of your controller, just make sure you get all the wires back in the same locations.



1986 6.9 glow plug relay, about 30 dollars at NAPA.

Incase you don't see them, the small green controller wire is on the terminal at the end of the metal strip labeled GLOW PLUGS, the small yellow wire in under the other end of the strip on the large terminal of the relay opposite the battery terminal.

Ok, I have a question. In the wiring between the starter relay and the glowplug relay, there is a plug. I'm not getting juice from the starter relay through to the glowplug relay which I hear is quite common due to burnt wires. My question is this: can I put a toggle switch from in the cab with juice and hook it onto the glowplug terminal on the glowplug relay? If I flip the switch juice will go there, and when I flip it off will the glowplugs have cycled?
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Old 11-17-2009, 07:51 PM
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Are you talking about the main power wire going to the battery terminal of the glow plug relay?

I just checked your user page, I guess we are talking about your 90 model?

Two different glow plug systems, relays in different locations and wired differently.
So when talking glow plug systems, the year of the truck is critical.

You are talking about the connector circled in red in the top picture?
It is very common for a bit of resistance in the connector to cause it to get hot.
After it gets hot a couple times, the connections in the connector carry little or no power to the glow plug relay battery terminal.
When the glow plugs system is heating and all of the glow plugs are working, it draws 192 amps.
So the switch is a bad idea unless you run big wire and a high dollar switch that can handle 200 amps.
A relay is the only way to control the power to the glow plugs.

If the connector looks like it has been hot, melted and deformed plastic, the repair involves cutting the two large wires which should be yellow or tan on your truck close to the connector on both sides.
Now splice them around the connector and insulate the splice so it can not short out.
Once you get full power to the relay, it should work like it is supposed to.

I also have to say that the top picture is an 86 or older glow plug system and there are a few extra parts, so yours don't look exactly like that.
But the basic locations for the engine to chassis wiring harness connector is the same.
Wire colors are different and the 7.3 has more wires in the connector.
 
 
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