Charging problem
Thread Starter
|
New User
Joined: Nov 2001
Posts: 13
Likes: 0
From: oxford USA
Charging problem
Ive got a 77 F150 with a 302, for the last 14 years the charge guage has been messed up , the needle goes from the center line all the way past the "C" very rapidly. It still charges fine but it makes all the lights on the entire truck blink like a strobe!! My grandfather said it has done it since he'd bought it from the original owner. I have been through a new cluster, altenator,regulator,solenoid,new cables, added ground wires,I even switched the field and stator wires around and the guage stopped jumping up and down but it wouldn't charge!! Does anyone have any ideas what Im missing or another solution I could try? thanks hd1
Postmaster
Joined: Feb 2003
Posts: 4,043
Likes: 4
Charging problem
I'm not sure how the ammeter can cause the lights to blink. The way the ammeter works thought there should be a shunt (a large guage wire) that carried the majority of the current. There are 2 small guage wires that go from under the hood to the ammeter. In the wiring harness from the alternator to the starter solenoid is where the shunt is located. I would pull the harness out (it should go from the alternator to the regulator and starter solenoid) and check it to be sure the shunt has good connections.
Now that I think of it you should be able to measure with an ohm meter from the ammeter connections back through the harness and see a low resistance connection through the shunt. If you unwrap the harness you'll see what I mean.
The ammeter connection should be a two wire plug near but seperate from the starter solenoid. You could also just unplug this connector and if the alternator stops charging the battery then I would say the shunt is the problem. Or just try replacing that harness.
Now that I think of it you should be able to measure with an ohm meter from the ammeter connections back through the harness and see a low resistance connection through the shunt. If you unwrap the harness you'll see what I mean.
The ammeter connection should be a two wire plug near but seperate from the starter solenoid. You could also just unplug this connector and if the alternator stops charging the battery then I would say the shunt is the problem. Or just try replacing that harness.
Posting Legend
Joined: Sep 2001
Posts: 30,255
Likes: 37
You have an intermittent connection somewhere in the charging or power distribution system. It could be anywhere from the fuse panel or ignition switch down to the alternator or battery. You don't say if this ammeter jumping occurs with the lights on, off, or both.
Posting Legend
Joined: Sep 2001
Posts: 30,255
Likes: 37
Yeah, the gage is just indicating that there is an intermittent current flow, doing what it is supposed to...
That type of broken connection can destroy your alternator. It is what is called a "Load Dump" transient that can put 400 volt spikes into your electricals.
That type of broken connection can destroy your alternator. It is what is called a "Load Dump" transient that can put 400 volt spikes into your electricals.
Thread Starter
|
New User
Joined: Nov 2001
Posts: 13
Likes: 0
From: oxford USA
Charging problem
Thanks for the input guys, Ill try the shunt idea. Im a NAPA jobber out of NY and you know not one of my RAYLOC reps mentioned that idea to me. That makes a lot of sense compared to what other guys have told me. This irratic guage happens as soon as the engine starts, lights on or off, and I have put a charging system analyzer on it and it does charge 13.5v- 14.5 again it bounces back and forth like the guage in the truck. Again I thank you for the input on this and Ill try the shunt, Ill let you know how I make out.--- THANKS hd1
Thread Starter
|
New User
Joined: Nov 2001
Posts: 13
Likes: 0
From: oxford USA
charging problem
Well guys I changed the shunt in the harness and I still have the same problem, do you have any other ideas? Thanks hd1
Trending Topics
Posting Legend
Joined: Sep 2001
Posts: 30,255
Likes: 37
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
AEV FXL Super Duty - the Super Duty Raptor Ford Doesn't Make
Brett Foote
Lobo Vs Lobo: Proof the F-150 Lobo Should Be Even Lower!
Michael S. Palmer
Ford's 2001 Explorer Sportsman Concept Looks For a New Home
Verdad Gallardo
10 Best Ford Truck Engines We Miss the Most!
Joe Kucinski
2026 Shelby F-150 Off-Road: Better Than a Raptor R?
Brett Foote
2027 Super Duty Carhartt Package First Look: 12 Things You NEED to Know!
Michael S. Palmer
10 Most Surprising 2026 Ford Truck Features!
Joe Kucinski
Top 10 Ford Trucks Coming to Mecum Indy 2026
Brett Foote
5 Best / 5 Worst Ford Truck Wheels of All Time
Joe Kucinski
Posting Guru
Joined: Jul 2001
Posts: 1,613
Likes: 2
From: Gainesville, FL
HD,
Get a voltmeter and check the potential 9voltage0 at you alternator. See if its spiking there. My guess is: your voltage regulator is shot. It's mounted on the passenger fender.
Secondly, the blinking lights could be a symptom of a bad headlight switch. Are your headlights blinking as well?
KingFisher
Get a voltmeter and check the potential 9voltage0 at you alternator. See if its spiking there. My guess is: your voltage regulator is shot. It's mounted on the passenger fender.
Secondly, the blinking lights could be a symptom of a bad headlight switch. Are your headlights blinking as well?
KingFisher
Thread Starter
|
New User
Joined: Nov 2001
Posts: 13
Likes: 0
From: oxford USA
charging problem
OK, when my gramps had this truck 14 years ago,it needed a water pump,while he was changing it he moved the alternator up out of the way,the B+ shorted out against the engine block.He said that evey since then the guage was irratic. The problem now that I have is ... When I get in the truck and start it up lights on or off the charge guage is rapidly moving from D-C,while its running it charges fine ,but when I pull on the headlamp switch the lights (all lights interrior and exterrior) will pulse like the guage does. I have changed the guage , solenoid, voltage reg.,altenator,voltage reg wire ends , added grounds, used a jumper wire as a ground in various spots, and changed the shunt.I just can't figure this out its making me nuts!! Headlamp switch???? Thanks guys!! hd1
Elder User
Joined: May 2003
Posts: 967
Likes: 0
From: Southern NJ
Might as well, doesn't sound like you have too many more options left as far as what could be causing the problem. If the system was shorted, I'd check the wiring itself too. One of the wires may have been overheated and melted the insulation. Thus crosslinking to the other wires next to it. What happened to my dash harness. Unwrap the lighting wiring, seems it would only be in that circuit from the indicative symptoms.
Posting Guru
Joined: Jul 2001
Posts: 1,613
Likes: 2
From: Gainesville, FL
HD,
I asked earlier if your headlights were flickering! You've got a bad headlight switch. It has a circuit breaker built into it and its shot.
Replace the headlight switch.
Good Luck,
KingFisher
I asked earlier if your headlights were flickering! You've got a bad headlight switch. It has a circuit breaker built into it and its shot.
Replace the headlight switch.
Good Luck,
KingFisher