voltmeter sudden drop - 2002 Excursion
Thread Starter
|
Elder User
Joined: Jun 2008
Posts: 612
Likes: 0
From: Iowa
voltmeter sudden drop - 2002 Excursion
2002 7.3l 4 x 4 Excursion Limited - the voltmeter usually runs about 12 volts at cold start and jumps up to 14.0-14.2 after the glow plugs shut off ( 13.8 with headlights and foglights on). The last 3 times I drove it the voltage stayed at 12.0-12.2 volts, 11.8 with the headlights and foglights on. The vehicle is still starting ok.. new batteries 8 months ago. 130k miles total on the vehicle.
question 1 : how do I disable the gpcm to make sure its not faulty and drawing 100% of the time? can the vehicle run without it?
question 2 - how do I jumper the terminals on the voltage regulator for full alternator charge?
question 3 - is the regulator built into the alternator?
all troubleshooting tips welcome,,, would rather not just throw parts at it.
also, where do I get real ford manuals at? have a 2000 f350 drw 4 x 4 and this ex I'd like to get manuals for.
question 1 : how do I disable the gpcm to make sure its not faulty and drawing 100% of the time? can the vehicle run without it?
question 2 - how do I jumper the terminals on the voltage regulator for full alternator charge?
question 3 - is the regulator built into the alternator?
all troubleshooting tips welcome,,, would rather not just throw parts at it.
also, where do I get real ford manuals at? have a 2000 f350 drw 4 x 4 and this ex I'd like to get manuals for.
Thread Starter
|
Elder User
Joined: Jun 2008
Posts: 612
Likes: 0
From: Iowa
bump back to the top with more info -
took it out this afternoon after reading the gpcm pinpoint test posted here on fte( did a web search and there it was, y'all can take a bow for posting that just for me). I turned the climate control off ( first time in the 2 years I have owned the beast, has the automatic system) and took a drive out to the farm. It got up to 13 volts at 75 mph... not its usual 14 but at least it is charging some. I turned the a/c backon for the return trip and it stuck about 12.2. I am guessing more alternator/ regulator now.
Is the regulator separate or inside the alternator? way to jumper the alt for full charge to check it?? Mind you I have no lights, no codes, just watching the aftermarket voltmeter and it changed ranges suddenly.
took it out this afternoon after reading the gpcm pinpoint test posted here on fte( did a web search and there it was, y'all can take a bow for posting that just for me). I turned the climate control off ( first time in the 2 years I have owned the beast, has the automatic system) and took a drive out to the farm. It got up to 13 volts at 75 mph... not its usual 14 but at least it is charging some. I turned the a/c backon for the return trip and it stuck about 12.2. I am guessing more alternator/ regulator now.
Is the regulator separate or inside the alternator? way to jumper the alt for full charge to check it?? Mind you I have no lights, no codes, just watching the aftermarket voltmeter and it changed ranges suddenly.
Of the next Riffraff East
Joined: Oct 2004
Posts: 8,679
Likes: 2
From: Concord NC
Sounds like you have a faulty Glow Plug Relay that is not dropping out. You could just unhook the the wires and see if your voltage returns to normal. Shouldn't need the glowplugs now.
Hotshot
Joined: Jan 2002
Posts: 17,988
Likes: 207
From: La La Land
As Barry said above, you can just unplug the GPCM temporarily. It will set a code, but not-to-worry.
Your field brushes could also be reaching end-of-life, and will not make good contact with the slip rings, resulting in reduced alternator performance. The charge rate will be less than normal, and your batteries will eventually start to go flat, resulting in a crank-but-no-start.
Pop
Your field brushes could also be reaching end-of-life, and will not make good contact with the slip rings, resulting in reduced alternator performance. The charge rate will be less than normal, and your batteries will eventually start to go flat, resulting in a crank-but-no-start.
Pop
Posting Guru
Joined: Jul 2004
Posts: 1,777
Likes: 0
From: Buckingham, IA
Use a VOM and check the voltage on the big terminal on the back of the alternator. That way you will know what voltage the alternator is putting out without anything else in the circuit. Sounds like you may have an alternator going out but this should help isolate the problem.
Hotshot
Joined: Jan 2002
Posts: 17,988
Likes: 207
From: La La Land
Anytime a lead-acid battery drops below 75 percent of full charge, sulfation begins to happen. That's about 1.225 specific gravity. Each time the electrolyte drops below that mark it adds a little more coating to the plates.
It's a cumulative process, which eventually covers the plates, eventually resulting in a "dead" battery.
Keeping them as close to fully-charged as possible increases their lifespan considerably, and one kept fully charged can last a LOT of years. Ask your phone company about their back-up batteries.
Here's a primer on it:
http://www.wisegeek.com/how-does-sul...-a-battery.htm
Pop
It's a cumulative process, which eventually covers the plates, eventually resulting in a "dead" battery.
Keeping them as close to fully-charged as possible increases their lifespan considerably, and one kept fully charged can last a LOT of years. Ask your phone company about their back-up batteries.
Here's a primer on it:
http://www.wisegeek.com/how-does-sul...-a-battery.htm
Pop
Trending Topics
Thread Starter
|
Elder User
Joined: Jun 2008
Posts: 612
Likes: 0
From: Iowa
disconnected the gpcm... turned off all electrical, still 12.0 at idle, would creep up to 12.6 at highway speed. I got a new alternator in from napa.... back to its old self. 13 volts idling cold, coming back to 14 battery volts slowly at highway speeds. Thanks for all assistance guys. I think its time to throw a gpcm in the parts stash... my luck it will die the first day of the coldest week of the year and not have nything locally available.
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
3 Best / 3 Worst Parts of Modern Ford Ownership
Brett Foote
10 Amazing Upgrades That Solve Common Ford Truck Owner Headaches
Pouria Savadkouei
Every 2026 Ford Engine Explained
Brett Foote
10 Ugly Ford Trucks That We Still Kinda Love
Joe Kucinski
10 Things Every Truck Owner NEEDS (2026 Edition)
Michael S. Palmer
Rezvani's Latest Post-Apocalyptic Monster Is a Ford F-150 Raptor Underneath
Verdad Gallardo
Top 10 Most Expensive Ford Trucks Ever Sold on Bring a Trailer
Joe Kucinski
2027 Ford Super Duty Buyer's Guide (Every Model, Engine, & Package)
Brett Foote
Top 10 Ford Truck Tragedies
Joe Kucinski
Fleet Owner
Joined: Jun 2004
Posts: 25,090
Likes: 1,112
From: Rio Rico, AZ.
You can disable computer control of your glow plug relay very easily by disconnecting the small signal wire from the driver's side post.
I forget the color code right now, but it's the small wire that does not get 12v when the ignition is switched on first thing in the morning.
The glow plug is controlled by completing the circuit to ground on that post.
If you want to control it yourself, like I have, then simply run a new wire into the cab from that same post, then to a simple momentary on push button switch and from there to ground.
What I do to start my truck now is to push the button and turn on the ignition, and start it when the wait to start light goes out or even a little sooner if the weather is warm.
Then I release the button and the charge rate goes straight to 14v because the glow plugs are now turned off.
Engine is a little smokier first thing in the morning, but so what, it's a cold diesel engine!
Soon as I drive off it clears out.
I also have run some jumper wires to the battery from the alternator.
Doing that made a HUGE difference in the charge rate at the battery posts.
Much more stable charge rate.
I forget the color code right now, but it's the small wire that does not get 12v when the ignition is switched on first thing in the morning.
The glow plug is controlled by completing the circuit to ground on that post.
If you want to control it yourself, like I have, then simply run a new wire into the cab from that same post, then to a simple momentary on push button switch and from there to ground.
What I do to start my truck now is to push the button and turn on the ignition, and start it when the wait to start light goes out or even a little sooner if the weather is warm.
Then I release the button and the charge rate goes straight to 14v because the glow plugs are now turned off.
Engine is a little smokier first thing in the morning, but so what, it's a cold diesel engine!
Soon as I drive off it clears out.
I also have run some jumper wires to the battery from the alternator.
Doing that made a HUGE difference in the charge rate at the battery posts.
Much more stable charge rate.
Thread
Thread Starter
Forum
Replies
Last Post
R0adwarri0r
Pre-Power Stroke Diesel (7.3L IDI & 6.9L)
14
Oct 1, 2015 11:13 AM
radmacks
Excursion - King of SUVs
25
Aug 29, 2014 07:31 PM
67F250RET
1967 - 1972 F-100 & Larger F-Series Trucks
9
Feb 1, 2013 08:51 AM
2002, 73, alternator, drop, drops, low, meter, powerstroke, signal, sudden, voltmeter, voltometer, vot, warm, wire
