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1988 Ranger Battery Draw


bill88

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1988
Make / Model
Ford
Engine Size
2.9
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Manual
My recently-acquired 88 Ranger 4x4 had a weak battery one morning, then was dead the next. The battery was still under warranty, so jumped it and took it to the shop. I wasn't impressed with their trouble-shooting skills, but they eventually said the battery had a dead cell and they swapped it out with a new one. Two days later, the battery was dead again.

Put a charger on the battery and got it to 12V. Then put my multimeter at 10A DC inline between the negative battery terminal and the negative cable. I have a 2.6 A draw with everything off.

I pulled the fuses in the cab out one at a time and the draw never stopped. I then pulled the green and yellow cables off the solenoid terminal where the positive battery cable connects, and the draw was gone. Put the yellow cable back on and no draw. Put the green back on and the draw was back.

The green cable apparently powers all the lights. I'm assuming I have a short somewhere. All the lights work when the cable is attached and I can't see any that stay on.

Any hints on where the short may be or how to track it down? Is there any usual place the wiring gets rubbed raw?

Thanks!
 


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martin

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1991
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I don't have the diagrams for an 88 but are you sure that the green wire only does the lights, I have a suspicion it also goes to the alternator. Try unplugging the alternator and see if it stops the current draw.
 

cocoasranger

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A bad diode in the alternator will draw down a battery when the truck sits. That happened to me. Have the alternator checked at the auto parts store. You might also want to pull the bulbs out in the glove box and under hood light to see if bad or mis-adjusted switches are keeping them on; an easy thing to check. Good luck.
 

bill88

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1988
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Manual
Thank you, both. I disconnected the alternator and the draw was gone. I had the auto shop check it out and it was bad. Just finished installing the new one. No more battery drain. Much appreciated!
 


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