Glow Plug Controller Bypass Option...

[TBigLug]

I've read all the threads on bypassing the controller but they all seem to center around eliminating the controller all together. I'll explain what I want to do then you guys tell me what you think. Why would or wouldn't it work?

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First off, where does wire B go?

Secondly, can I unhook A and run a wire from it to a momentary switch in the cab while leaving A hooked up? That way the automatic cycle is still there for when the wife drives the truck but it'll be easier to get that extra four or five seconds if it doesn't start on the first try.

My thought is that I can use the momentary switch to increse my burn time four seconds to help on the coldest mornings. This came about in that I keep my truck plugged in at night but when I go to work I had no where to plug it in. I turned the key forward after it had been sitting in 13 degree temps for about 5 hours, glow plugs burned for 10 seconds, hit the key, cranked over but no fire. Turned the key off then back on to try and cycle the plugs again but the light only came on for a second and went off. I guessed that it sensed the plugs were still warm and wouldn't let them cycle again. Cranked again for 10 seconds or so and got nothing. Just turning over slower than I liked and smoke from the tail pipe. Finally I jumped out and used a screwdriver to connect the two posts under the cap and counted to ten, jumped back in the truck and it fired right up.

Since then I have replaced the two 650 CCA batteries that were in it with two new (less than a month old) 850 CCA batteries with the thinking that the lack of juice from the small batteries just wasn't enough to heat up the glow plugs enough to start it. When I was doing the tranny fluid and filter change (long story, some days you're the bug) the truck sat where it couldn't be plugged in for a couple days in around 20 degree temps. I jumped in, cycled the plugs and it started but not too easily (in my LIMITED opinion based on VERY LIMITED experience). My last 6.9 I NEVER plugged it in, even on the nights where it stayed near zero and it always started.

So, will my plan work or will it backfeed and hurt something if I leave both hooked up?

 

[Goofyexponent]

B is your WTS light in the cab IIRC.

That is all I did for A. I ran a fused wire to a push button, and then tied into that wire on the firewall side of things. My wait to start light still works, and the controller still functions as it always did. My wiring was a mess from day one, so this is the best solution I could come up ith for my truck

 

[Agnem]

B is just a ground wire. Remove either A or B and it won't work. A is the control wire, and the one the controller operates. Why not just build a new controller? I pioneered this circuit many years ago.

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[SparkandFire]

Good schematic for the controller, Mel. Using the triple-5 chip as a one shot would eliminate the need to hold the button in, and you could adapt a PTC thermistor to adjust your glow time based on outside temperature.

 

[TBigLug]

B is just a ground wire. Remove either A or B and it won't work. A is the control wire, and the one the controller operates. Why not just build a new controller? I pioneered this circuit many years ago.

Looks like a nifty deal, but out of my league. I'm just a simple dirt-farmer.

That and I already have a switch that would work.

What is that thing made out of? Is it some kind of custom circuit board?