Adding a manual button to '85-newer glow controller

A couple of years ago, I updated the glow controller system on my '83 K2500 to the '85-newer controller (with the resistor mod). Everything works well and it starts great except when it's over about 95 degrees outside and the truck has sat for less than an hour since it was last ran. The glow controller will not cycle the plugs at all and this engine needs some glow at all temps. I want to add a manual momentary switch to cycle the glow plugs manually when the controller doesn't turn them on during these hot days. Does anyone know how to wire in a momentary button that could be used when the regular controller doesn't cycle? I have an original old-style glow plug relay and momentary button to use, just not sure how to get it set up.

Hi Bob
I haven't done it myself...
But there should be a trigger wire on your new style controller.
You button would be supplying 12V to that wire on the controller.Someone once mentioned putting a diode in the original wire so you don't back-feed the sensors.

Installing a GP override with a momentary switch is simple, but may not be necessary if you want it to go through the glow cycle at every start. Simply move the GP controller to the fender, away from the engine (heat). The temp sensor that's inhibiting warm cycles is inside the controller.

The controller doesn't have a "trigger" (exciter) pole. The relay is controlled internally. Ign. power just starts the glow controller cycle, and not specifically the relay.

If you still want to add an override, you'll need a relay (Ford starter relay highly recommended, and cheap, but you can use your original 83 relay), relay mount hardware (screws/bolts), lengths of 10-8 AWG wire (Batt+ power and relay to GP power), lengths of 16-14 AWG wire (momentary switch), eyelet connectors (3/16 and 5/16"), and harness protection (split loom, electrical tape, zip ties, etc.). No need for a diode. It won't backfeed to the controller. The existing fusible links are inline with the GP harnesses, but you will want (need) a 10 amp inline fuse for the momentary switch power.

Attachment 7182

Thanks guys. I actually have the newer controller mounted on the driver side fender where the old relay was located. That's why I was a little surprised it was affected that much by the heat. At first, I was wondering if there was an issue with this particular controller (it was a brand new AC Delco unit).

Appreciate the information. I still have a good relay from the '83 glow system and I have a momentary switch. I'll start collecting the other items too.

I installed a manual glow plug controller not too long ago. I'm attaching the wiring diagram I used and a few pics. I removed the original glow plug controller and installed the relay for the new manual system in its place. I made a small plate for the new relay to sit on that would allow it to be installed in the same place as the original controller. I mounted the momentary-on push button switch next to the rear window defogger, next to the steering wheel. The power that runs to the push button was pulled from the fuse block - IGN circuit 39, which passes through the 20A GAGES fuse. For the relay I used: Standard Motor Products RY139. For the momentary-on push button switch I used: Gardner Bender GSW-22.

BobQ, I had the EXACT problem that you are having: when the engine was just warm enough that the internal switch on the glow plug controller would open, I would have very hard starting - sometimes it wouldn't start at all. This is what instigated me to install the manual controller. During the installation process, I figured out that I had a weak set of batteries which lead to not enough heat build-up in the cylinders because the starter was not rotating the pistons fast enough. I replaced the batteries and the original system worked fine (as it has for the last 30 years) at the warm engine temperature mentioned. I ended up continuing to install the manual system. It works great and I have not had a problem with it. I do worry that someone will hold the push button down for too long, or generally misuse it, which will lead to a headache with swollen glow plug tips.






Attachment 7198
Attachment 7199Attachment 7200Attachment 7201Attachment 7202Attachment 7203

Thank you for the information and wiring diagram.