Glow Plug Relay not shutting off after 30+ secs.

[DavidJBlythe]

All,
I just replaced all my glow plugs with 60G's and put my put the controller card back in. I used to hear the relay click on and off after 5 - 10 secs on the old wellman plugs, but now the relay closes as I turn the key on, the wait light comes on for a few secs, goes off, but the relay doesn't close. I waited for 30 seconds and then turned the key off, not wanting to burn up my new plugs.

I looked at TM9-2320-289-20, but it doesn't cover this situation.

Any ideas?

 

[antennaclimber]

To clarify your description of your situation.
"but now the relay closes as I turn the key on, the wait light comes on for a few secs, goes off, but the relay doesn't close."
Do you mean it "doesn't open" after the wait light goes out?

If so, check a couple of things.

Low batteries will cause this condition.

or,

The controller card is sensing a low voltage on the glow plug side of the glow plug relay.

Check your battery voltage when the GP relay is closed and check the voltage on the glow plug side of the glow plug relay when it is closed.
Karl

 

[mistaken1]

What voltage do you see on the load side of the glow plug relay with the key off and again with it on?

 

[kentuckycucv]

I just changed mine 2 weeks ago and it does the same thing. My Card is good. did the 12v bypass. How many seconds at 12volts does it take to burn up ac60g plugs. How long is normal?

 

[DavidJBlythe]

Sorry for the confusion. Let me write it a bit differently:

When I rock the key on, I hear the glow plug relay go "clunk" as it engages. My gauge in the truck goes from 12v to about 10v, normal in my truck when the plugs are warming.

After about five seconds the "wait" light goes out, but I don't hear the relay let go. My gauge is still at 10v.

It will continue like this until I turn the key off. When I turn it off, I hear the relay open back up with a different sounding "clunk" and the gauge goes back to 12v.

I will check the voltages with my meter and report back. One thing I did in the interim was the resistor bypass. It took all of a few minutes and I feel a bit better not having to worry about providing more than 12v to the plugs. I checked the operation after making the conversion and there was no change.

Thanks for the help. It will likely be tomorrow when I can get to work on it again, but that's only because Alabama is playing today! Roll Tide!

 

[doghead]

Is your orange voltage sense wire on the GP side of the relay? It needs to be.


The relay can and will stay on after the wait light goes out. Have you simply confirmed with a DVM that the relay is saying on(over approx. 15 seconds).

 

[tbearatkin]

My relay will click on and off as I drive down the road. This is when it is hot. I have not had time to troubleshoot it so I do not know if its a bad temp sensor on the back of the engine block or a bad PC card. My orange wire is on the GP side.

Right now my temp fix is once the vehicle is running and warmed up I take the blue wire off the relay.

I have found out as I drive down the road with the blue wire off my wait light will come on sometime. It never does that when the blue wire is on the relay instead the relay is clicking on and off (volt gauge drops) but no wait light.

 

[hokie8358]

i am having similiar issues with mine. i ve got new relay in and just friday put in the new temp. sending unit. still my relay will keep firing the plugs for up to 4 or 5 minutes. i also thought it was rule of thumb to always run the 13G's by a.c delco, as these were designed for the militay 6.2's cause they were slow burn. the 60G are fast burn. in the past i ve replaced more burned out 60's than i have 13's.

 

[DavidJBlythe]

Ok. I checked the voltages. I have 12.7 on the battery side. When I close the relay, I have 10.7 on the GP side. I checked each glow plug wire and got 10.7 on each one. I also completely removed the relay and cleaned it and all the ring terminals that were on it. Once everything was shiny, I put it all back.

 

[doghead]

Sounds like a bad relay. The voltage should be the same on either side under load.

 

[tstone]

In any of my CUCV's that have had issues with glowplug modules, I have disconnected the modules and installed a manual momentary contact switch (which closes the firewall solenoid) and a pilot light that indicates when the plugs are energized. I have used the "blank" where the radio would normally be mounted to install the switch and pilot light. I use the switch to close the contacts on the firewall relay and mimick the factory program for energizing the GP's. The pilot light will help confirm when the GP's are energised so that you can eliminate GP burnout. I've used this set up on several of my trucks and it works well.

 

[doghead]

A manual push button will not fix a bad relay.

 

[DavidJBlythe]

Can I go with any replacement relay or do I need to get an exact part number replacement? Any good ones recommended?

 

[doghead]

ST-85 or GP-109, both have been used successfully.

Whatever you buy, before installing it, test it with an ohm meter and be sure there is no continuity between the small terminals, to the mount(chassis).

The correct relay needs to have the coil isolated, because the GP controller switches ground to the coil, to operate.

 

[DavidJBlythe]

I did a simple test today. I pulled all the leads off of the glow plugs and turned the truck on. The wait light stayed on for about 25 secs, and the relay finally opened back up after about 65-70 secs. I didn't want to actually subject the plugs to this.... 70 secs seems a long time for a 60G to be cooking. Thoughts?

Also, I checked the voltages again. When the plugs are on, the voltage on both sides of the relay are around 11v. (with the plugs connected, controlled via a manual switch).

Should I be checking the controller card or temp sender at this point? I didn't get any resistance (ohms) across the sender when it was cold. It seemed wide open.

Again, thoughts?

 

[mistaken1]

I believe you should have 800 ohms minimum with the engine cold on the yellow wire (according to the -20 TM).

Do you have the TMs in pdf format? Searching in them is a breeze.

 

[kentuckycucv]

Thanks guys... My GP relay was making theclunk noise when I turned the key but no voltage out the bottom with the orange wires to the glow plugs. Just got the S603 at Oreilys and the glow plugs (ac 60g 12volt bypass) got voltage, and the truck fired up in 2 seconds.

 

[kentuckycucv]

I checked my gp controler card and it looks good. no burns etc. But My new gp relay energizes my glow plugs too long. Today I started the truck and it seemed like it stayed energized for about 40 seconds. I have the ac60g plugs, did the 12 volt bypass. have the orange wires on the bottom of relay.
How many seconds should the glow plugs be energized in 60 degree temperature? And How long does it take to fry them?

 

[kentuckycucv]

In any of my CUCV's that have had issues with glowplug modules, I have disconnected the modules and installed a manual momentary contact switch (which closes the firewall solenoid) and a pilot light that indicates when the plugs are energized. I have used the "blank" where the radio would normally be mounted to install the switch and pilot light. I use the switch to close the contacts on the firewall relay and mimick the factory program for energizing the GP's. The pilot light will help confirm when the GP's are energised so that you can eliminate GP burnout. I've used this set up on several of my trucks and it works well.

I think this is what Im going to do as well. What kind of pilot light did you use, and did you just splice into the orange wire to the gp card harness? also since my GPs are staying on for too long i guess i need to disconnect the blue wire off of the relay and install my leed for my switch.

 

[cpf240]

I think this is what Im going to do as well. What kind of pilot light did you use, and did you just splice into the orange wire to the gp card harness? also since my GPs are staying on for too long i guess i need to disconnect the blue wire off of the relay and install my leed for my switch.

I would think any 12v light that you like could be used, and just tie it into the GP side of the relay. You could even use one of the 12v LED bulbs if there is any concern of the bulb taking away from the current available to the GPs, but I doubt that is really a concern.