2001 Excursion Voltage Drop

[leswhitt]

So I have a 2001 Excursion and when I turn the key, the voltage will drop (measured at the batteries) to 10.5 for about 45 seconds. After that, they'll come back up to 12.3-12.5 and everything is normal but it was getting harder and harder to start. The last two times I've started it, I've had to get a jump because the batteries were too low....I think there's a parasitic drain as well.

I initially thought it was the glow plugs so I unhookd the GP controller and it still did it. The next thought was the fuel pump but I pulled the relay and still had the voltage drop, now I'm fairly certain that I have a short somehwere.

To narrow it down, what system on the truck kicks on for ~30-45 seconds and then stops? I'm ohming everything out and found that the issues lies with the two rings that affix to the relay on the fenderwell, one of them draws 2 amps when the key is turned to "on" and the other draws just 1 amp. Any thoughts?

 

[79jasper]

Still sounds like glow plugs.
Try removing single fuses at a time.

 

[FordGuy100]

How old are the batteries?

 

[leswhitt]

The batteries are about 6 months old but I haven't had them tested yet. I replaced the other batteries because of similar symptoms, I wish I would've tested it first....

My thought is still on the glow plugs as well, why would the voltage drop if I disconnected both the positive and negative terminals on it? I didn't remove the smaller wires on the post, they seem much to small to draw 2 amps without burning up. Maybe the trigger wire in the harness has a hole in the insulation and is grounding out? If that were the case, it seems like a fuse would've blown by now though.

Last night I made a 70 minute run to another city and when I turned the truck off, the batteries were very weak and wouldn't spin the motor more than twice despite my Scangauge reading 13.6-14V the entire trip there. I wonder if the alternator is going bad and causing the problem? I plan to have it tested either today or tomorrow, hopefully that'll rule out one more variable.

 

[79jasper]

The batteries are about 6 months old but I haven't had them tested yet. I replaced the other batteries because of similar symptoms, I wish I would've tested it first....

My thought is still on the glow plugs as well, why would the voltage drop if I disconnected both the positive and negative terminals on it? I didn't remove the smaller wires on the post, they seem much to small to draw 2 amps without burning up. Maybe the trigger wire in the harness has a hole in the insulation and is grounding out? If that were the case, it seems like a fuse would've blown by now though.

Last night I made a 70 minute run to another city and when I turned the truck off, the batteries were very weak and wouldn't spin the motor more than twice despite my Scangauge reading 13.6-14V the entire trip there. I wonder if the alternator is going bad and causing the problem? I plan to have it tested either today or tomorrow, hopefully that'll rule out one more variable.

The glowplug "trigger wire" is actually a ground signal. IIRC.

Very well could be the alternator.

You could pull the wires off the alt and see if it still drains overnight.

 

[leswhitt]

Well, after further review, I was looking at the intake heater relay and not the glow plug relay. Since my truck is an Excursion, it actually has a glow plug command module and not a relay, what that translates to is $$$$... That being said, more research has shown that the voltage drop is normal when the glow plugs energize and not a short as suspected.

Moving on, it appears that the parasitic drain is the issue and that's what I need to get to the bottom of. I'm going to test the alt and batteries at lunch, hopefully that'll give me some insight and I can fix this once and for all.

 

[79jasper]

I was going to have you take a pic, cause I was thinking all ex's are "California emissions." Which get the glowplug control module like that. (IIRC)

But I've heard they can for sure cause problems.

 

[leswhitt]

That being said, more research has shown that the voltage drop is normal when the glow plugs energize and not a short as suspected.

Moving on, it appears that the parasitic drain is the issue and that's what I need to get to the bottom of. I'm going to test the alt and batteries at lunch, hopefully that'll give me some insight and I can fix this once and for all.

I think I'm going to backtrack here...I don't think it's normal that the batteries are dropping to 10V. Plus, there are two plugs that go into the module, one is black and one is green. When I disconnect the black plug, the voltage stays at a normal 12.6 v AND it responds much better to when I charge the battery. Whem I leave it connected and turn the key, that's when the voltage drops to 10-ish. Disconnecting the green plug has no effect, the voltage stays the same whether it's connected or not.

Now I'm a tad confused, I don't know if the module is the problem or if it's the alt. I suppose I could still test the alt as I initially intended too... Does anyone know if there's a procedure to test the module? I'd rather not start throwing more parts at it since I already replaced a starter that didn't need it.

 

[79jasper]

Not sure of a test procedure.
Is it easy starting?
No smoke?

 

[RenoF250]

I think you still have a bad battery. If the voltage is getting up ~14.2V when the engine is running the alternator is doing its job. You say you drove it with good voltage and it would not start soon after that cannot be the alternator, parasitic load, or the glow plugs. The glow plugs will not even turn on if the engine is warm.

 

[RenoF250]

I just went and checked mine - 12.34V > 11.6V with ignition on > 12.05V running > 14.3V running after GPs off.

This was measured with a Fluke at the DS battery terminals.

My batteries are not new but turn it over just fine. I have the CA GP controller as well.

 

[leswhitt]

It's been awhile but I think the problem was a bad ground AND a battery draw from the radio. The battery draw was from one of the large cables, it looked great but had internal corrosion because it had a good amount of resistance. I replaced it and things were much better. I was still getting a draw though so I went though everything and once I disconnected the radio, it would sit for 3-4 days with no problem of starting back up.

In the midst of plugging/unplugging the GP controller when I was testing it, I think it fried. In our 25-35 degree temps, I MUST have the truck block heater plugged in or else it refuses to start. I would've already ordered another one but I'm in the process of selling the truck and focusing on an International MDT instead.