You don't want to put it on the PCM's output. The reverse is what you want to do.

Pull the wire OFF the PCM. Then, when that removed wire gets a ground, the WTS lamp will light.

Run that wire to a relay that is creating a switched ground with its contacts, and trigger the relay's coil with power from the output from the GPR.

When the GP's are getting power, so is the relay's coil. That closes the contacts between the wire to the WTS lamp and ground.

The glow plugs are on? So is the WTS lamp.

Kapeesh?

Pop

 

no...

Sorry...

I guess a wire from the hot lead of the GPR is just too easy...LOL

 

Have you looked at the wiring diagram of the instrument panel?

That might explain it for you.

Pop

 

Pop, your explanation makes perfect sense, and also demonstrates it's easier just to add an LED off of the 12V #4 stud on the GPR. So it'll either be in the dash gauges or it'll be dangling until I make a decision about adding more gauges to the pillar.

Thanks for the clarification,
-Chris

 

I thought about looking in to disconnecting the WTS light from the OEM (PCM) connection and then wiring the WTS light up to the GPR... but I just ignore the WTS light now (as far as starting) and monitor the LED, which I mounted in my A-pillar gauge pod.

 

Not to pick on you...
I remember when the mod came out some people would wait for the full two minutes and then start their truck. This does get things good and warm and the truck should start. You have to remember the glowplugs don't just help start the truck they help keep it running! The romp romp is one example of what happens when your glowplugs don't work properly. This is bc your combustion is barely happening due to the cold engine etc. If you have a hard on to wait the full two minutes you better be recyling them so they are on when you get the motor running.
I remember one kid just freaking out. It was something like, "I can't believe the moron engineers have messup up something else on these trucks..." I assume he was a kid, for all I know he was a grown man. Most of his posts sounded...immature. Pop and papadelogan were around that post IIRC, maybe they remember it as well.

 

I should have visited this thread again sooner. Too many things to reply too but springer is onto my thoughts as well as torquemister.

I dont really care how much longer the GPs are on compared to the WTS light. I just want to know that they are still on when im starting. As it is, mine is just the little curly logo and it doesn't say "wait to start" like my 99 does. Thanks for the info springer, so a little relay and ill be all good to use the light in the dash which will be perfect. And its still the black/pink wire too.

 

Not quite. The glow plugs don't need to operate once the engine starts. You'll get a lot of white raw diesel smoke if they aren't on when the engine is cold, but for all intents and purposes, once the cylinders are firing they should keep firing regardless of whether or not the glow plugs are on.

The "romps" are caused by high pressure oil starvation inside the injectors, not because the glow plugs are working or not.

 

From my experience with diesels they make a lot friendlier noises and considerably less smoke when the gps are working/on. Maybe it is in my head.

I though HPO starvation was one cause of the romp that was compounded by bad gps. My bad.

 

Well, there we have it by Cleatus12r,""" The "romps" are caused by high pressure oil starvation inside the injectors, not because the glow plugs are working or not.
__________________This question has been going on now and everybody had their own theriory, thanks Cody..

 

I finally got around to installing my gp LED and was actually surprised to find that the glow plugs don't necessarily turn on just because the "wait to start" light comes on. In fact they only lit on the first start of the day and even after sitting for about 3 hours they still weren't activated. I always assumed that when the WTS light came on the gp's came on. So what's the deal with the WTS light then? Does it just default and light up for a set period of time every time the ignition is turned on no matter what? That's a really stupid light if so, tells me nothing. No sense in waiting to turn the key if the gp's aren't even lit. I guess that's why I installed a light lol...

 

Yeah, I was going to just install a push button switch (as recommended by Dan) to override the PCM's control of the GPR but I decided to do this LED mod first so I can see how much the GPs are really used. If I think the GPs are being overused and therefore shortening battery and GP life, then I'll add Dan's override switch and keep the LED to monitor that the GPR is working.

 

Just installed mine today. Great, inexpensive mod. I was also surprised at after the truck had been running, the GPs never cane on the rest of the day on re-starts,however the WTS light was always on. Must be WTS light PCM controlled regardless of temp, and the actual GPR ground provided by PCM must be temp related.