Glow plug relay?

[English Paul]

Like others on here I have a starting problem on my 2000 7.3. The SES light comes on and no glowplug/wait to start.
Try switching on and off many times and eventually the glow plug relay clicks and the wait t s light comes on for a couple of seconds, then the SES light comes back on as the wait light goes out. Eventually after cranking a few times the wait light stays on and goes out as normal and it starts ok ish, sometimes stalls, but re- starts ok. Then no problems.
No codes are showing. So I guess the glow plug relay could be faulty? Over to you guys!

[NoRalPh]

NO, that's Not how the system works...

The WTS light and the relay are unaware of each others condition. All the WTS light is doing is letting you know that the PCM sent the signal to the relay to turn ON (in fact, your GPs are on for Much longer than the light is lit)

If you have no WTS light, chances are your PCM isn't running at that time.

If you have a SES light, you HAVE codes, you're just trying to use an OBD-II scanner on your truck and it's Not the right equipment you need

You might need a relay, but you need to diagnose what's actually wrong though first -> Troubleshooting GPR & GP's

[7.3Lifted]

When my GPR went bad the WTS light still functioned as usual, no SES light and also no codes. From what I have gathered, the WTS light is not a indicator of whether your GPR is functioning or not, because of this some members have wired in a fuse and LED to the GPR to act as a indicator light.

If you think its your GPR you might as well take alook at this write up.Troubleshooting GPR & GP's

[English Paul]

Thanks. I will check the gpr tomorrow. While I agree about the OBD tester, when the gpr is working etc there is no SES light on. The only time the SES light is on is when the WTS light doesn't come on!
Anyway, I will see how gpr tests go, I have a spare pcm - so that may help if the relay is ok.
Once again, thanks for your help.

[7.3Lifted]

Thats weird, NoRalPh's post wasn't there when I read the thread or even when I went to preview my post.... I post, and then it appears

Anyways, I agree with his post.

Do you have a chip? I had a similar problem when I had a faulty chip.

[English Paul]

Originally Posted by 7.3Lifted

Thats weird, NoRalPh's post wasn't there when I read the thread or even when I went to preview my post.... I post, and then it appears

Anyways, I agree with his post.

Do you have a chip? I had a similar problem when I had a faulty chip.

Interesting. I do have a chip with stage 2 injectors. Can't remember the make, came from Beans.
Lots for me to try tomorrow. We are about 7 hours ahead here, so I am off to bed soon. I will post how I get on as soon as I have news.

[NoRalPh]

I had a thought.....

If you had a bad temp sending unit, the PCM might have a code saying it was over limit (hence the light) AND it would also NOT engage the GP relay and you'd have no WTS light.

Gotta get a good scan

[English Paul]

Good point. Tried to start this evening. The gpr isn't engaging while the wts light isn't coming on and the ses light is on. OK, after switching the ignition switch on and off about 50 times, the wts light came on and you could hear the gpr engage, the ses light went out as soon as the wts light came on incidentally, and when the wts light went out the motor started as normal. No more ses light. Ran it for a while and switched off. Went back after 15 mins and it all worked fine. Most strange.
Will check further next week when I am not so busy fixing other folks cars and bikes! And I will try and get the codes read - not so easy over here.

[jtomasik]

I don't want to start yet another thread on the glow plug relay, but I discovered mine wasn't working. When I directly grounded it on the cold side of the ignition circuit, it works. Does the small wire coming off the relay (not the hot one from the switch) go directly to ground, or does it go somewhere else?

[NoRalPh]

On the small terminals, one side is supplied with 12v, the other goes to ground when the PCM supplies the path. That's how the PCM controls the relay, by supplying ground.