I just started having a cold start problem with my '02 Excursion this fall and I'm at my wits end trying to fix it. Truck starts fine above about 45 degrees and when it's warm. If I plug in the block heater it also starts fine in the cold. If it's not too cold I can eventually get it started by continuing to crank it. It blows white smoke while cranking and for a few seconds after it finally turns over. Smells like fuel. Runs rough for 30 sec after starting when it finally turns over. Definitely seems like glow plugs aren't working. This truck started no problem on GPs alone without plugging in down to -20 deg F before this year.

I started by cleaning all battery connections, including the two ground posts on the engine block, I replaced one bad battery (diagnosed by Autozone; other one was OK), I checked the resistance of the glow plugs (only a few years old with about 30k miles on them) through the connectors on the GP control module (all were about 1 ohm), and confirmed 12V at the power pins in the GP control module connectors. I then replaced the GP control module and the problem is still present. Battery voltage drops from about 12.6 V before I start the GP cycle to about 12V when I turn the key to "ON" and the GP light comes on. How much should the voltage drop when the GPs are on? What the heck else could be wrong??

 

It sounds as though maybe one or more of the glow plugs are not doing their job.

I see a drop from 12.6 at key off to between 11.2-10.7 volts on mine when I first turn the key on an the GP's are powered.

Which brand of GP's did you install when you replaced them 30k ago?

 

Should throw a code in an Excursion if a glow plug is bad. Might be your Glow plug control module. Exes have them instead of gpr's.

 

No codes. Autolite glow plugs. All test good (around 1 ohm). As I said, I replaced the GP control module. No improvement. Considering JHL3's post that he sees his battery voltage drop to 11.2 - 10.7 V when the GPs are on and I only see it drop to about 12V, it looks like the GP control module is not sending voltage to the GPs when it should be, even though I'm seeing voltage at the power input pins on the two connectors going into the GP control module. I'll have to check for voltage at the wires going from the module to the GPs themselves when the GP cycle is active. I can also check for a signal from the ECU to the module. What voltage should I be seeing from the ECU when it's telling the GP module to send power to the plugs?

 

Auto lights aren't recommended for sure, as well as only replacing 1 battery. Have you scanned for codes? I know when my gpcm was going out I had a code for all drivers side glow plugs bad. Then I replaced it and had a code for one GP, so I just replaced them all on that side with Motorcraft. I can't remember if it was a soft code or not.

 

^^^^X2^^^^

I would replace those Autolite GP's ASAP. The tips swell over time until pulling the heads becomes necessary to remove/replace them.

Excellent advice on replacing both batteries at the same time also.

 

I put autolites in my truck before I learned of all the problems with them swelling and getting stuck in the heads. I lucked out. The following winter after I had installed autolites, 4 of the 8 had already burned out and weren't working. I've been running 3 years now with motocraft plugs and no problems. I've also noticed an improvement in cold weather starting using Lucas fuel additive. Summer starting it makes no difference and I don't see the mileage and performance improvements the bottle claims, but cold weather starting is better for sure.

 

I'm going to throw in my agreement on ditching those autolite's for motor craft as well as replacing both batteries at the same time. The old battery will pull voltage from the new one and will shorten the life expectancy of the new one.

 

No codes at all.

I've just read a bunch of horror stories online about Autolite plugs, so I'll be replacing them with Motorcraft plugs this weekend. However, I still don't think that this is going to fix the problem. The Autolite plugs have worked great up until this fall (started right up at -20°F without being plugged in) and they all still check out with perfect resistance.

I did put in a TS Performance 6-position chip this past spring to replace my Quadzilla module after it died. I'm going to try removing this chip to see if the GPs start working again. Even in the "stock" position, I'm still having hard starts. I read a post from 2006 about a guy who was seeing this behavior with a TS chip in his Ex. I'll update this thread after I do this.

 

I doubt the chip is effecting the function of the GP's. You have one of a couple of issues. You have (1) a bad harness or GP control module, (2) bad compression, or (3)worn poppets on your injectors. I doubt it's compression, it is more than likely (1) or (3). How many miles does the truck have?

 

I replaced the GP module as part of the troubleshooting process so I doubt the new module has the same problem as the old one. The truck's only got 130,000 miles on it and it started great in the cold just this past winter. It doesn't seem likely that it could lose that much compression or the injectors could wear that much in the 5 or 6,000 miles I've put on it since then, but I suppose anything's possible. If it's not the chip then I'm leaning towards wiring or possibly the ECU itself. Any idea what voltage I should be seeing on the signal wire from the ECU to the GP module when it's calling for the plugs to heat?

 

You could try a GP test on a AE. That would help you get closer to the problem.

 

I doubt it is compression and probably isn't injectors either at that mileage although my injectors went at 150,000 miles. I will dig around and see if I can find that voltage number.

 

Measure battery voltage, then voltage drop with key on/wait to start(glow plugs on) to see if glow plugs or system is functional.

As others have said, replace then soon, even if they are working.

 

For the trucks equiped with the glow plug relay, the ECM sends out a ground signal when the glow plugs are called for. I am not sure if that works the same way with the glow plug control modules on the Cali trucks and Excursions or not.