Problems using the electronic glow controller in parallel with manual control

[argo]

I have been using the Automatic glow controller on my Sub for nearly two years now with no problems. One day, however, the controller gave up. Since I have 60G plugs, I just hot wired the controller with a jumper cable, got the engine started, and drove home. I replaced the controller, and everything was peachy once more. I decided that I wanted a manual glow controller as a backup, however. So I got the requisite Ford starter relay and installed it along with a momentary push button. I just extended a lead from the hot side of the factory glow controller to the relay, and ran a jumper from the relay output to the controller output terminal. As soon as I started reconnecting the batteries, I heard the electronic controller click. With the key off, it activated itself. I unplugged the electrical connector on the controller and it shut off. I checked for feedback voltage, and the only place I get it is on the sensing lead, and that is only when the manual push button or the glow controller activates the plugs. I am at a loss as to how or why this is happening. Right now I have the plug to the electronic controller unplugged and I am using the manual controller. Any thoughts on why this is happening?

[More Power]

The Ford relay should be a "normally open" relay, which completes the circuit only when activated. As such, it should not affect the other controller when the power lead connection is made. It could have an affect when the Ford relay is powered, because the original controller will then be seeing 12v on the output side of its relay.

Should work regardless.... I haven't heard of anyone else having a problem when a 2nd relay is wired correctly.

Jim

[argo]

That is what I was thinking. I just wanted a second opinion. I disconnected my manual relay just to check the controller and surprise surprise! It doesn't work. I guess I need a controller.

[Liftgate]

Yesterday I was working on my 84 suburban under the hood and had it open. It was hot and the sun was shining on my new updated glow plug controller. I have had the engine running the day before with the new glow plug controller setup but didn't start it yet this day. When I tried to start it, it just cranked and cranked. I didn't hear the controller relay thump like it should. I closed the hood and waited for the sun to go down and then came out and tried to start the engine. I heard the relay thump and it started no problem. I am thinking about wiring a manual glow plug energizing setup so I don't get stuck somewhere in a situation like that. Any ideas about how to wire the manual setup? Thanks.

[sctrailrider]

I sent you a message with a link to a good write up for this mod....

[argo]

Yesterday I was working on my 84 suburban under the hood and had it open. It was hot and the sun was shining on my new updated glow plug controller. I have had the engine running the day before with the new glow plug controller setup but didn't start it yet this day. When I tried to start it, it just cranked and cranked. I didn't hear the controller relay thump like it should. I closed the hood and waited for the sun to go down and then came out and tried to start the engine. I heard the relay thump and it started no problem. I am thinking about wiring a manual glow plug energizing setup so I don't get stuck somewhere in a situation like that. Any ideas about how to wire the manual setup? Thanks.

Here is how my setup is wired. (By the way, my system works fine now that I replaced my glow controller.)

Materials needed:

8-10 gauge wire (2.5mm-3.5mm) for the heavy load circuit

18-22 gauge wire (0.7mm-1mm) for the control circuit

4 heavy duty eyelets with a 3/8" (10mm) hole

assorted spade, eyelet and butt connectors

Automotive style 30 Amp relay

Ford Starter Relay

Momentary Push Button Switch

2 inline fuse holders

2 amp fuse

30 amp fuse

Setup:

Find a suitable mounting place for the 30A relay and the Ford starter relay and your momentary switch.

Wire one fuse holder to an Ignition hot source (there should be ignition hot taps in the fuse box; otherwise, tap in to the gauge circuit) and install your 2 amp fuse.

Run a wire from the fuse holder to the momentary switch.

Run a wire from the momentary switch to terminal 86 of the 30 amp relay.

Run a wire from terminal 85 of the 30 amp relay to a suitable ground.

Run a wire from the hot side of the glow controller to the 30 amp fuse holder.

Run a wire from the 30 amp fuse holder to terminal 30 on the 30 amp relay.

Run a wire from the 30 amp relay terminal 87 to the Ford starter relay "S" terminal.

Run a heavy gauge wire from the hot terminal of the glow controller to terminal "B" of the Ford starter relay.

Run a heavy gauge wire from terminal "M" of the Ford starter relay to the output terminal on the glow controller.

As usual, I will now warn you to make sure you are using PTC type glow plugs that self regulate like AC Delco 60Gs and blah blah blah... you know the drill.

Some people prefer to run the momentary switch to the Starter Relay, but I don't and here's why. The Starter relay can draw up to 30 amps when activated. Most momentary push button switches are only rated for 2-5 amps. Also, you don't want to add 30 amps of additional load to an ignition fed power source, even if it is only momentary. The 30A relay isolates the light duty components from the relatively high current flow of the Ford starter relay.

[DmaxMaverick]

That's good advice, if you want/need the glows to be wired into the ign circuit. I wire them always hot, so the GP's are used before the ignition is on (no PCM-GP activity on later models, and easier battery load, and no additional ign switch load). The momentary switches I use are "starter" switches, or toggles (spring loaded to open), rated at 30-50 amps. No under-dash wiring, other than passing the switch wire pair from the solenoid to the switch. Otherwise the same as the above post. On non PCM vehicles, I replace the OEM GP relay with the Ford relay, with the GP harness routed directly from the relay (fully manual system, then). If you want automatic operation, wire as Argo described, but use a timer relay (small), and adjust the duration according to the desired GP cycle (always test with the GP harness disconnected, so you don't fry the plugs the first time). I recommend setting them for moderate climate starts, and it can be cycled twice for colder starts. The timer also prevents excessive glow cycle durations, which shortens GP life. If you mount the Ford relay (large) to sheet metal or chassis, the audible "clunk" when operated is easily noticed (removes doubt, even if the lamp doesn't work), and you don't have to run an independent ground circuit (grounds through the mount tabs). I recommend the simplest method that meets your needs.

[argo]

I really like the idea of the timer relay. I should have gone that route to begin with, as well as having the manual button as a backup. If this GP controller fails, then a timer relay will most likely be the solution. If it were only me driving the Suburban, it would only be manual glow operation. However, since it is my wife's family wagon, I needed it to be wife friendly. :)

[Liftgate]

sctrailrider, argo, DmaxMaverick, thank you all for the input. I am going to have to think about how I want the wiring, always hot or only with the ign on. Do all I need is a 2 or 3 amp momentary toggle for the manual glow plug switch? Also, can I just use my old good GP relay in place of the Ford starter relay? I am gonna reread argo's post again. Thanks.:)

[DmaxMaverick]

You could use your OEM relay, some folks do. The Ford relays are $15 or less, carry the current better, and are more reliable. Use the small switch ONLY if you are (small) relaying to the (large) relay. If you are using only the OEM or Ford relay, you'll need a 30-50 amp switch, and NOT through the ign circuit (always hot).

[argo]

Liftgate: I realize now that you have the earlier glow setup, not the controller/relay combination of the later trucks. Your job is even easier than I described. You can wire the control circuit as I described with the small 30A relay and just wire the relay's output to the control input for your current relay (what would have been the "S" terminal on the Ford Starter Relay). You can either make it ignition hot or you could make it hot at all times (just wire your momentary switch to something hot at all times instead of ignition hot if that's what you want to do). Or you could forgo the relay and use a heavy duty momentary switch to carry the current needed to activate your glow relay as DmaxMaverick suggested. I prefer to use the 30A relay to do that so I don't have to run high current wires into and then back out of the cab, but there is nothing wrong with that. It comes down to personal preference, either will work and be reliable. Just know that if your glow relay ever fails, the Ford Starter Relay is better and cheaper to come by than the GM glow relay, and as mentioned, it carries current better.

[Liftgate]

Argo I do have the newer updated glow controller. I changed over a few weeks ago. Gathering parts together now for the manual glow plug setup and was wondering where I can get a 2 amp ATC fuse? How about the 30 amp 12volt relay with a timer? Any ideas? I am using dieselrx glow plugs and controller. Don't know if they are PTC glow plugs.