Installing resistor to increase glow plug cycle time

[Jeffrey12]

I have a 1993 3/4 ton 6.5 and I want to add a resistor to increase the cycle time on my glow plugs. I seen some threads here awhile back and am unable to find them. I would like to get some information about doing this and how to do it.

[More Power]

A 5-ohm 2-watt resistor installed in the pin-C wiring lead of the glow plug electrical connector will ad about 4 seconds to the initial cold glow cycle time. This is enough to allow an 18:1 compression engine to cold start just like a 21.5:1 engine.

The online Troubleshooting Guide will show you more detail about the electrical connector.

The exact value isn't too important. Some have had a hard time finding a 5-ohm 2-watt resistor. A 6 or 7 or 8 ohm will also work, with corresponding increases in glow time. You could also use a pair of 10-ohm 1-watt resistors in parallel.

Do not extend the glow times unless you have the newer PTC style glow plugs (i.e. AC-60G or Kennedy's). The older AC-9G or equivalent could burn out with extended glow times.

MP

[cruzer]

Where do you shop for these resistors?
Someplace like RadioShack?

[More Power]

Radio Shack, an electronic component supply store, or a consumer electronics repair shop (repair center for VCR's, TV's, stereos, etc.) should have what you need.

I found 5-ohm 2-watt resistors at an electronic components store here in Missoula, Montana. They sell all sorts of switches, resistors, capacitors, diodes, IC's, batteries, you name it.

You could also order online from www.digi-key.com (http://www.digi-key.com) or some other electronics supply. The resistor is a 2-bit part though...

MP

[BuffaloGuy]

I added the resistor per More Powers instructions. It worked like a charm all summer but now I'm finding I need a little more glow time. I went to the mountains and between the elevation and the cold it started pretty hard.

I'd like to add a switch so I could add glow time before I turn the key. Since we lost all the old posts where I know it was described can anyone help with this project?

Ken

[wilpulu]

Buffalo Guy,

Just wired one up on my truck. Went to auto-parts store bought a starter solonoid, I don't think it matters what kind just as long as it will handle 40 or 50 amps. Ran 4 gauge wire from accesory post on fuse box to solonoid and then 4 gauge to passenger side glow-plug controller post and then wired a switch into cab. You are gonna want to run a 60amp or higher fuse in the accesory box. Hit switch for about 8-10 seconds, turn off switch, turn key and let a normal cycle run and I get smoke free easy starts. You have it hooked up right if the wait to start light comes on when you hit the switch. Hope this helps you out.......later

[rjschoolcraft]

Aside from a manual switch, can you extend glow times on the electronic trucks?

[More Power]

Ron,

A second relay wired in parallel seems to be the best solution at this point in time for extending glow cycles on the electronic trucks. Push a momentary button for 5 or more seconds, release the button, then turn the ignition switch to the run position to allow the computer to run through its normal glow cycle. The two glow times added together return cold starting ability of an electronic 18:1 engine to normal. You'll only need to worry about extending the glow cycle when the temperature is below about 40 degrees F.

Secondarily, you could acquire a Peninsular glow timer that cycles the plugs for a predetermined length of time. However, the 1994 and newer vehicle computer will set a glow system code if the glow plugs are on when it thinks they shouldn't be. That's why a second relay should be used with the ignition OFF.

wilpulu,

When selecting a relay and wiring, you need to add together the 16 amp draw for each of the eight glow plugs, which equals 128 peak amps through the relay. The AC glow plugs I've tested can draw up to 16 amps each when stone cold. To build in a little longevity in the relay, you should select a relay capable of at least 150 amps.

MP

[Jim P]

I put a manual glow plug button on my 95 that just puts juice to the yellow wire on the glow plug relay. I also put a diode in the yellow wire between the relay and the computer to keep any juice from back feeding into the computer when glowing manually. I can hit the manual button anytime and it never sets a code. I even use the manual button to after glow and this way it never makes any smoke on startup. That is really nice if your parked somewhere where you don't want to create a smoke screen that is big enough to cover half a parking lot. With my 18:1(maybe even a little lower) engine, if I don't extend my glow time and our house windows are open, my wife says that I completely fill the house with smoke that smells like raw fuel.

I wait for the glow plug light to go out and then give it another 5 seconds with the manual button and then it starts instantly. After it starts, I turn the glows on for a second off for a second etc. for about 10 seconds and it makes no smoke whatsoever.

[BuffaloGuy]

Just got done adding a relay set-up to my '93. It took me about an hour and $28 in parts. I used a ford solenoid ($8), a spring loaded heavy duty push button switch, 6 gauge wire and a fuseable link. Works like a charm. As mentioned the glow plug light comes on with the key off and the button pushed and then when the key is on it seems to cycle just fine. The real test will take some cold weather.

The DP is sure great help!!!

[GaryC]

I tried the setup Jim P had done and could not get the glow plugs to come on with the switch.I guess I must have wired somthing wrong.I checked and it did have 12volts going to the yellow of the connector with diode going back to the pcm. I guess I will start from scratch and wire in a second relay parallel.
Jim P. if you read this let me know if I left something out.
Thanks

[Jim P]

Gary,

It seems like you did it right. You do have to have the key on for it to work. Other than that, the only thing that I know might be different is that yours is a different year than mine.

[GaryC]

Jim P.
Thanks
I had one of them brain cramps......I was trying to make it cycle manual with the key off. Works like a charm

Thanks again

[Ralph Fichtl]

Ok, tell me what I did wrong. I took a 5ohm 2watt and install it on the black wire (pin c) coming from the glow plug relay. My engine would not start.
I have a 98 Suburban "F" 6.5TD

Thanks Ralph

[Svante]

Hallo from Sweden. does anybody knows if the glowplugs handles 12 volt. Mine is marked with 10.5 V I want to make a manuel glowing but I am not sure if I just can add 12 Volt to the plugs via a pushbutton to the relay and then to glovplugs???
Svante

[rjschoolcraft]

Ralph:

The resistor trick only works on the 93 and older mechanically injected trucks.