Hello everybody, I have glow questions and a few people told me this was the place to ask them.

I'm working with an '84 Isuzu 1.8 liter motor, but I've been told this glow system is the same for all Isuzu motors.
Glowplugs are new.
The glowplugs stay on for less than a second then switch off. The relays are good. The sensors are good as far as I can tell, as unplugging them makes no difference. The sensor by the thermostat is good, as when I disconnect it the glow system doesn't engage at all. The only thing left I can think of is this QOS box. I tried to order one from an Isuzu dealer, but the car the motor is in is not an Isuzu, and the dealer had never heard of a QOS. I did a search here and found a few posts stating there are schematics somewhere for bypassing or building a new timer module, if this is the case I would greatly appreciate instructions or advice on what to do now. I have switches, I have rheostats, I have wire, etc.

Thanks for your time and any help you can provide me!

Try a google search like this Isuzu Diesel glowplug
Use the advanced feature in Google to add this domain http://www.4x4wire.com/forums/
Anyway we have discussed the glow plug controller many times as you will see with this search

Right I just registered, you have to tell me to search first and go use google, a second-rate search engine at best.

If anyone has a helpful reply I'd appreciate it. No searches anywhere here or any search engine have produced any schematics of a bypass or DIY clone of the QoS module, a few here and there talk of writing one up one day. I know I can just hook up a switch and reduce the glow plug voltage from 12v down to 6v with a rheostat but I was hoping find a few time-tested methods of rewiring it to still incorporate the sensors.

Thanks

Hello - Outfit Boss, gave you some good advice. I know it takes a while to search through all those threads but there is a PDF doc somewhere that talks about the diode failure in the glow plug controller. Here is a simpler solution. Go to a dealership that sells and services Thermo King Refrigeration Units or sells Isuzu Generator sets with your controller in hand and match one up. You may have to swap out connectors for a plug and play connection but as you indicated in your first post they are really all about the same as long as you match the cylinder numbers.

There are other problems that can cause the same (on briefly and then off) glow malfunction, one I can name right off would be lack of power to the relay(s). Have you checked the heavy-gauge power wiring and fusible links yet? This particular issue has been discussed here before, there may be more to it but that is my recollection.

Additionally, the plugs are not 6V, they are 12V units. The 'cold' glow supplies them with full battery voltage, while the 'warm' mode runs the current through the large resistor first. I imagine this resistor's presence in the system is where the rumor started.

Did you even look at the link I posted? You are welcome.

Acy
I have to agree with you, they aren't 6v...mine are 5 volts. Marked right on them. Burn out in about 6 seconds on 12 volts too. Ask me how I know. <img src="/forums/images/graemlins/evil.gif" alt="" />

They heat up real quick on 12v, then get the second stage at reduced current through the resister.

Ah, I see... I stand corrected.
Well, I think we can all agree that Isuzu does in fact supply them with 12V on high glow, at least. I've only looked closely at the wiring, not at the plugs themselves - but 12V on high is factory wiring unless my memory is incorrect.

Have you seen Jerry's diagram for a replacement controller here ? Might help figure out the operating regime.

THANK YOU!!