Manual glow plug wiring

[joshua bebbino]

Good afternoon all, I have a quick question , I'm trying to figure how the previous owner wired the manual switch , I have read and watched all the videos on this subject and still can't figure out how he did it. The relay has a red wire that runs to the switch under the dash it's attached to the top of the relay and a black wire that's attached to the relay on the front which runs to the switch on the dash. Correct me if I'm wrong but shouldn't it be a wire connected to the relay at the front which runs to the switch and the a wire from the switch to a ground? I have been having trouble starting the truck lately and figured I would start troubleshooting the glow plugs first . Any help would be greatly appreciated. Thank you

 

[acthomp781]

Hello. I would suggest to start with downloading the wiring diagram. That way you can see what is supposed to be there and what was added by the PO.

 

[doghead]

Maybe the relay is grounded by it's mount(incorrect original part)?

Pictures and explanations of the wires terminations would help us figure this out.

Do you have a control card installed, and if so, does it work?

Or, is the manual switch the only way that makes your glow-plugs work?

 

[Matt5]

I would put it back to stock as the TM's show...

For now I would assume that switch just engages the relay... when you hit it do you hear the relay click?

If so check your glow plugs they may be burned out...

Was this system ever working? Is the truck new to you first winter?

 

[joshua bebbino]

When i hit the switch i do hear a Clunk sound, glow plugs were checked with a test light and I do have (1) which is not working the other (7) light up the test light. Truck is very had to start and a decent amount of white smoke while cranking. Rebuilt starter was installed last month along with electric fuel pump and spin on fuel filter.

 

[joshua bebbino]

There is a controller card installed, however I believe he disconnected the light blue wire and ran a black wire from the front of the relay to the switch. So i guess the manual switch is the only way for the glow plugs to work. This isnt the first winter , However i have always had a really tough time starting the truck which has lead me to adding a electric fuel pump, spin on fuel filter, rebuilt starter and doghead starter relay mod. In the attached picture I have drawn two arrows that top arrow is the red wire that runs to the manual switch and the bottom arrow is the black arrow which also runs to the switch. Thank you for taking the time to answer.

 

[Matt5]

To quickly test, flip the switch to glow and make sure you are getting power to the plugs. Also how long are you holding this for your location is "new york" first thing in the morning you are looking at a good 10 seconds if not 15 of glow needed...

I have also never used the test light to check the GP, I have always measured resistance.

Smoke means you are getting fuel but it is not lighting.

 

[joshua bebbino]

When I first got the truck the guy told me to hold for 12-15 seconds so that is what I have been doing, 10-4 i will measure the ohms of the glows after work today. With the batteries fully charged when I attempt to start its sounds like its just about to kick over but never makes that final kick, you can hear the starter spinning but it just never makes it past that and then the batteries eventually get weak. Thank you for your help Matt5

 

[joshua bebbino]

also, what is that red wire for that is run from the top of the relay to the switch? Ive read almost every post on the manual switch and don't recall reading two wires running to the manual switch? I could be wrong as well, just trying to get to the bottom of this. It has been a pain to start the last two years and I have almost switched out all the major components aside from the IP pump which i originally thought was the problem.

 

[Matt5]

The test light method may work fine I do not know, but .8 to 1.8 ohms IIRC is correct for the plugs anything outside of that is "bad"... I would think the test light would only not light if the circuit was open. I would assume (maybe wrong) that plugs that are not good (outside of spec) may still light the test light but fail the ohm test... IIRC you must pull the plugs to test ohms... I could be wrong on that. You could also have low compression but I assume the motor runs fine ones it gets going?

Either way white smoke should be fuel so you just need heat and RPM to light it.

That is where I would start, make sure all the plugs are at that .8-1.8 range, and make sure they are getting power. Simple and free to do. If your plugs are still hooked to 24volts the bad plug should be replaced soon, over time (lets not debate how long here) the added voltage from the bad plug will kill the other plugs. If you find out you have multiple bad plugs I myself would replace all plugs with a60gs.

 

[Matt5]

also, what is that red wire for that is run from the top of the relay to the switch?

OKay so the top of that relay is hot all the time correct?

It is just power then to trip the relay assuming it is a power not ground activated relay.

Use the test light turn the plugs "on" and check for power at the plugs, I would also check voltage at the plugs.

 

[joshua bebbino]

Thank you Matt5 for this , Engine runs fine once going never had a problem with the truck once running, just the startup, however, I did have a few times when i ran the truck for a while and then turned it off and it would not start back up this past summer, I would cut it off run inside to do something and come back out and wouldn't even get it to crank, nothing , if i let it sit for a good 5 hours it would start back up. Had the batteries load tested and everything came back good. Then this has happened where i cant even get the truck to start. So this have been a on-going problem that i have not been able to get to the bottom of.

 

[Matt5]

With out getting too far off, I would still test the glow plug system operation.

When you say "Crank" crank means turn over, spin the engine... the motor would not even turn over, or it would turn over and not fire...? I just want to make sure we are both on the same page as to what "crank" means.

Not turning over at all, not spinning, let's ignore that for now.

Turning over but not firing when hot could be the IP, dumping cold water on it and trying to restart would verify that is the issue.

But as I said I would if it was my truck, test to make sure the glow plugs are good and the system is operating (power getting to plugs when switch is on) and then report back for all we know that relay is a ground activated relay that someone hooked power to and the GP system is not working correctly.

Also am I losing it did your location not say new york before? lol.

 

[joshua bebbino]

10-4, One problem at a time lol Okay, so i would put the key in and turn and get nothing almost like it was completely dead, not spinning nothing. I tend to agree with what you said that maybe the PO hooked this relay up wrong. I will check to see if I have power to the glow plugs when the switch is engaged and report back this afternoon. Yes i just changed it had forgotten to do that when I moved. Thank you for helping me with this Matt, very clear and easy to understand help. Thank you

 

[joshua bebbino]

Ok just checked the glow plugs they are getting power. However, the wiring diagram and what currently on the truck is totally different. Currently on the truck there are 3 red wires connected to the top of the relay, 1 goes to the positive term bar, 1 goes to i guess the resistors behind the air filter, 1 goes to the glow plug switch, all have 12 volts when switch is engaged. There are 3 orange wires connected at the bottom, and 1 black wire on the front that goes to the glow plug switch. everything attached to the relay has 12 volts. there also is a light blue and a pink with black stripe wire tapped together but not connected to anything. The relay says 12V SAM7-09. I'am totally confused, I printed up the wiring diagram and nothing matches. Any Help would be greatly appreciated.

 

[Matt5]

Okay let me just make sure I understand you correctly

Top of relay has 3 wires
1 wire going to the switch inside the truck
1 wire going to the 24volt bus bar (is this truck covered to 12v or still 24v?)
1 wire going to the resistor pack behind the air filter

This wiring is er, interesting...

I am going to stop right there and ask

Is this truck still 24 volts or has it be converted to 12
Can you double check the wiring on the top of the relay... and trace the wires back as far as you can go? Something is amiss here...

However, if when you hit the glow plug button you are getting 12 volts to the plugs, then I would check the plugs.

 

[joshua bebbino]

Yes, you are correct , 1 red wire going to the switch it's a smaller one, 1 red to the bus bar , and 1 behind the air filter, truck had been converted to 12 volt. Bottom of the relay has 3 orange wires. (2) big ones and (1) smaller orange wire. Then a small black wire on the front middle of the relay, once the switch is engaged everything has 12 volts. Im gonna change out the glow plugs this weekend , should I just replace the relay and switch as well and wirer it has said on the forum? Or should I just try to bring it back to a stock set up according to the wiring diagram? If the new plugs don't fix the problem. Also something to note , I use to here a whining sound when the glow plug switch was engaged , however that has since disappeared recently. Thanks again Matt

 

[MarcusOReallyus]

, I'm trying to figure how the previous owner wired the manual switch

The quick answer is, there's no telling what someone else did. The best you can do is to understand the RIGHT way, and just fuggedabout figuring out the P.O.'s mess. Just rip it out and replace it correctly.

 

[Matt5]

just want to make sure I have this right

Top of relay has 3 wires
1 wire runs to the switch in the cab
1 wire runs to the x24v bus bar
1 wire runs to the resistor pack behind the firewall

The small tabs are the tabs to trigger the relay er solenoid whatever...

The orange is output... that stuff sounds fine.

Not sure what is going on with that resistor pack deal... I would remove that the truck is 12 volts not 24 that is not needed and is just a hot wire that it asking for a problem... and maybe causing the problem?

You can not go back to stock because the truck is not stock my understanding (could be wrong I keep everything stock, no reason to change it) is that the GP card will NOT work with a 12v system.

Did you check the voltage at the plugs with the switch on?

I mean the switch appears to be triggering the relay because you say your getting power to the plugs (dident mention voltage)... in my mind this leaves a few things...
your not getting 12 volts (not sure whats going on with that resistor or how stuff is wired up at this point so takes 10 seconds to check if its 12v (11v whatever not 6v))
More than 1 plug is bad (ohm test to check I know that works not sure about test light method as I said before that my not show a "damaged" plug that is not getting as hot as it should)
Engine has poor compression (and has trouble making temp to ignite the fuel at start up but you said it runs fine so if it was that worn out we should see other issues)
You have some sort of fuel issue (but you state white smoke that is fuel... and you state it runs fine ones it starts... makes me think the timing is right and fuel is not the issue)

If you didn't sort of guess yet... my thoughts are going towards check voltage just because of that resistor being in the mix still who knows how anything else was wired, but more so... are all the plugs good?


The whine... mine would do that sometimes and sometimes not... it really does not tell us anything it worked making noise or not, maybe someone can tell us why they do (no idea) but ya should not matter for your issue.

 

[joshua bebbino]

10-4, I will check the volts to the glow plugs in the am, if there getting 12v I will change the plugs , if not I will try to figuring the restistor thing out, while I get the new plugs I'll also throw a new fuel filter on to cross something off the list, I will report back the status after all that in the morning . Thank you again