Electric Choke Has Constant Power?

Ranger84 · #1 03-14-2012, 09:44 PM

I have a 1984 Ranger with a 2.8L V-6 a 5-speed. The electric choke is getting constant power and it drains my battery. I traced the wire and it goes into a relay. I replaced the relay and it still has power going to it at all times. I was told by a friend that the choke is controlled by the computer on this year Ranger and I might have a bad ECM?

Does anyone have any ideas on what I should do next to try to fix this problem and get my choke operating as it should?

Thanks

Maritime Storm · #2 03-16-2012, 03:44 PM

Bear with me on this one but if I remember correctly the electric choke on a 2150 Motorcraft carb should get it's power from the center post of the alternator or at least this is how it was wired on my 1983 Mustang 3.8L/2BBL. If the diodes are leaking on the alternator you could have voltage being supplied even without the truck running. I haven't got the wiring schematic for your truck in front of me only for the Mustang but the wiring should be same set-up. If this is how yours is wired(and I suspect it is) then unplugging the wire at the alternator will answer your question if the alternator is the issue. On the 1983 Mustang, this wire was a white wire with a black tracer bolted on to the back of the alternator, my wiring diagram indicates this should be the same on the 1984 with a choke relay set-up, with the key off you should not have ground at the grey wire with a white tracer at the relay, if you do the choke solenoid valve may be bad unplug it to see if your power source at the choke goes away. The choke relay gets it's ground source from the choke solenoid valve. Not sure why Ford made this change but it was only done on 1984 & 1985 model years according to wiring diagrams in front of me. On my Mustang, the choke shorted and fried the alternator, after replacing the alternator and then I installed a manual choke to avoid a repeat as a choke heater couldn't obtained locally at the time. Hope this is of help. E-mail me if I can be of further help.

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Further note the ECM doesn't control this on the Mustang of these years, cannot say with certainty on the Ranger but I suspect it didn't on it either.

Ranger84 · #3 03-17-2012, 12:53 PM

Thanks for the tips. I won't have a chance to look at the truck untill tomorrow but I have already replaced the Alternator because my old one was bad, and I still have the same problem. I think that you are right about them being wired the same because the wire colors on my truck are the same as the wires in the mustang schematic you referred to.

I will let you know what I find out tomorrow.

Thanks again.

Ranger84 · #4 03-22-2012, 07:39 PM

Maritime Storm,

I unhooked the alternator and I also tried unpluging the choke solenoid valve but the wire to the choke still has power all of the time.

Do you have any other suggestions? I don't know what else I should try.

Thanks

Ponyguy · #5 03-22-2012, 10:16 PM

Hi, Ranger84
I have a 1984 Mustang and have the factory wiring diagram on my lap; the engine wiring is about the same as that of a Ranger.

The choke heater is grounded to the carburetor body, and the other end of the choke heater connects to the Alternator stator "S" circuit connection.
There should never be power applied to the choke heater unless the engine is running. Since you've already replaced the alternator (and I'm assuming that the new one is good), then I'd suggest you try checking the external voltage regulator; if the field switch is stuck closed in the regulator, it could cause the trouble you describe. Also, never dismiss the possibility of a defective replacement alternator.

With the engine running, there should be ~6-7 volts applied to the electric choke heater; the choke solenoid valve is also powered by this ~6-7 volts, which is part of the hot-engine restart system, and shouldn't have anything to do with your problem.

Also, be sure you check your alternator wiring and connections; hopefully, they're connected the way the factory designed:
"B" should be Black/Orange, going through some splice connections, fuse links, and ammeter shunt to the battery.
"F" should be Orange/Light Blue, and connect to the voltage regulator "F" terminal.
"S" should be White/Black, and connect to the choke heater.

Good luck!!

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Quote:

Originally Posted by Maritime Storm

Further note the ECM doesn't control this on the Mustang of these years, cannot say with certainty on the Ranger but I suspect it didn't on it either.

I'll concur with you, Mr. Storm.
ECM has no bearing on this system.

Ranger84 · #6 03-29-2012, 09:24 PM

Ponyguy,

I tried disconnecting the voltage regulator and even putting a new one on but I still have the same problem.

The wire on my choke heater doesn't go to the back of the alternator. It goes to the diagnostic port on the passenger inner fender well, it then goes to a relay on the passenger inner fender well.

I have attached some pics but it is kind of hard to tell what I am talking about. I took off the wire looms so I could trace where the wires are going. The first pic shows the choke heater wire that is grey going into the diagnostic port, and the second pic shows the diagnostic port and the relay that the wire goes into. I don't know if this helps anyone but I don't know what else to do or try.

Thanks.

Maritime Storm · #7 03-30-2012, 02:55 AM

It sounds like in this case you have a short in the wiring to the relay, unfornately this where your fun begins, time to start checking wiring until the find the source or consider swapping to a manual choke. None of my Ford wiring diagrams show a set-up on this engine that looks like what you have, but it does appear stock.