I bought a f350 that is a 94 the po had stock idi turbo on it he said the valves went bad in it and he wasn't smart about and just got rid of the whole engine and turbo (by the way this is all my history Bout the truck) he got a replacement engine not sure out of what but he said it was a 89 7.3 anyways he had this truck long time he been having cold start issues that's why I guess he sold it to me the first thing I did was change all filters and even had to do new starter and new electric fuel pump and at the time I didn't know bout the autolites being bad GPS so I've put a new controller for the glow plugs and the silinoid I noticed the wiring has changed instead of the 2 yellow wires he changed it to a big red wire but still wires from right fendersilinod to gpr that big wire a bad thing why did ford use the two small yellow ones

With those autolites the relay will click on and off Hella fast I know this ain't normal because my father in law also has a 7.3 idi and his silinoid clicks once and you.here go off a second click when the wts light goes off and his voltmeter don't bounce everywhere he also has motorcraft GPS but before I thought glow plugs again I went ahead did that manual switch and I got it to click only once and it clicking.off when I stop pressing the switch I got the autolites to work on the first try ever lol those plugs only lasted 4 cold starts with me counting to 10 sec for the cycle

I did replace them with the motorcraft ones and I then thought I wouldn't need the manual switch anymore so I hooked up the new controller and relay back up and I still was getting same results with the auto lights I know I'm getting power to the plugs because if not the manual switch wouldn't of worked either so I don't know whet to do I would like to stay away from the switch because my wife sometimes drives it so I need some help I was looking at wiring diagrams but almost no reason to simply Cuz it ain't stock but I can I would like to try to get back to its original wiring

 

what is it doing with the motorcrafts in it now?
on a cold engine the wait to start light should come on for between 10 and 15 seconds, then go out and you should hear the relay click for up to 1 minute after the light goes out. when the WTS light goes out step throttle to the floor and turn the key to start.
it should fire rite up.

 

With the new glow plugs the truck still had the hard start Issue I know I have power to the plugs if my manual switch worked I think that is correct how would I check the harness to make sure it's still good

 

Could there be any other wiring Probs if you want pics of the wiring from the start i can.

Oh yeah it still clicking like before as well but you know it summer and when I did that manual switch I only had them on 10 secs in 95 plus outside temp was that too long for them to stay on maybe that's why the autocraps went out after 4 manual uses that why I did switch back to the controller because I'm scared to burn these ones out the glow plug system seams really easy but I guess I'm that lucky guy who switched out every thing and still no dice I know I'm a ginger with no soul perhaps and that's why the truck is the way it is lol JUST FRUSTRATED by this lol 😂😅💩💩

 

Oh yes the wts light did stay on for the right time

 

Ok so today I went to my wife's work to pick up the truck we had no choice but to use it and she told me that it fired right up on the second try note she started truck mid day around 90 plus degrees outside and when I went to pick up the truck (because I don't want it not start with her having to use so I took the truck back and when I went to start it after 3 hrs I don't know if engine was cold or still warm but yes my glow plug relay and controller worked I heard one click when the wts came on and when It went off after about 7 to 10 seconds I cranked her and she fired up with no prob like the system worked for once I don't remember if the temp gage was on cold or just above it I don't remember but anyways I wanted to let you all know because I'm confused about it .one time when I still was using the autolites I had to get the truck at her work another time and it was about 3 hrs of it sitting in the heat and with the autolites the relay clicked non stop until the cycle was over and I'd had to sit there and crank the he'll of her till she ignited I just thought you would like to know some differences sorry for all this righting I just want to get her fixed properly

 

Slow down and write legibly. It's extremely difficult to follow your thoughts with run-on sentences.

If the PO has messed up the wiring harness just buy one of the brand new 6.0 harnesses on Fleabay and use it.
https://www.ford-trucks.com/forums/1...-for-50-a.html

I was having problems with my '89 7.3L glow plug system. I eventually found that the problem was loose fitting connectors on the glow pugs. I removed the remains of the factory yellow insulation on the connectors and put some heavy duty shrink wrap on them and problem solved.

 

I wanted to know if I could first test the harness before I make or buy a new one

 

Of course you can test the harness. I completely removed mine from the engine, pulled it out of the convoluted tubing and checked every wire for signs of overheat/melting.

Festus Hagen has posted some testing procedures. You can start at post #9 here:
https://www.ford-trucks.com/forums/1...ont-start.html

 

Hey I looked and looked at the thread link you sent but it still didn't show how to make sure the harness is good. I know the harness connects to the glow plugs does the harness connect to anything else??

 

it sounds to me like it is working properly. most autocrap glow plugs burn out within one or two uses whether the glow for 10 seconds, or 2 seconds.

hence why we call them autocraps.
the motorcraft ZD-9 plugs were designed for use with your controller.
auto craps were not.
the motorcrafts will still work after having power to them for 20 seconds. but they don't need to be powered that long, 7-10 seconds over 70 degrees or so, and around 15 seconds under around 45 degrees.
the glow plug controller should shut off after 110 degrees block temperature if it is wired properly because glow plugs are not need when the engine is hot.

 

OK I understand that.. anyways ways I got the controller to work with the motorcraft and the relay stopped clicking like it was with the autolites, but now I'm kinda lost because it still took 2 trys to fire her off in 85 degrees I know that the controller works because it wasn't clicking it actually clicked once and then click off. then on the second try it was non stop clicking but it fired up after 5 seconds when she fired up the relay was still clicking is that normal? Is that the afterglow coming on.
I still didn't get to check the harness yet but if that is the problem I'll let you know since that is the only other variable I think??

 

yes ,the clicking after the WTS light goes off is the after glow.
have you tried putting a test light on the output of the relay to make sure power is going to the glow plugs? that is the very first thing i do to any diesel i get in. i switched to 12 volt LED bulb a few years ago. but with the light i know for sure they are getting power instead of relying on the WTS light, because with the newer trucks the light will come on even if no power goes to the plugs.

 

I bought a new relay and controller and glow plugs so I'm pretty sure the relay is working and controller is to and I only have mutimeter not test light

To check the harness I guess I need someone to the key to on and see if I'm getting power at the connectors so since the controller kills the power after 10 seconds how can I check the harness propearly? Just keep cycling the plugs until I read all the connecters? Or is there a simpler way lol sorry if I'm annoying you or who ever is reading this

 

no problem. we all have ot learn these things, and it is a lot easier learning from someone that has been htere than trying to learn on your own.

the easiest way is to climb up in the engine and put the test light or meter on the glow plug relay output terminal or to one of the glow plug tips. then have someone turn the key to run. if you see power with the WTS light on, when it turns off when the light goes out, the relay is working. you should also see a burst of power when the after glow clicks.

like i said, i hook a 12 volt LED to the output of the glow plug relay and mount it in the dash. this way i know for a fact when the plugs get power and when they do not.