Battery Light on Dashboard - Ford Taurus 94

[Harold2810]

Hi

My Ford Taurus 94's battery light in the dashboard lights up on cold days when i change to reverse gear. But when i change to drive gear it goes away. Is there anything i could do to rectify it?

Thanks
Harold

[KimMG]

Check the belt and idle speed.

[shorod]

Originally Posted by Harold2810

Hi

My Ford Taurus 94's battery light in the dashboard lights up on cold days when i change to reverse gear. But when i change to drive gear it goes away. Is there anything i could do to rectify it?

Thanks
Harold

Are you making a pun here? Discussing the charging system and asking how to "rectify it?" For those of you that don't find the humor here, the alternator (part of the charging system) is a three-phase charging device that produces alternating current (AC). Since the automotive charging system uses direct current (DC), there are 6 diodes in the alternator to "rectify" the AC to DC.

Okay, if you're still reading, this sounds like an interesting issue. Does the battery light go out immediately when you shift out of reverse (ie: to neutral), or do you need to be in drive? Does it go out as soon as you shift to drive, or when you release the brakes and start to accelerate? If you're idling in drive with your foot firmly on the brakes and turn the headlights on, does the battery light come on?

As KimMG suggested, what does the engine speed do when you shift to reverse as opposed to when you shift to drive? I would expect the engine speed to be the same. If not, it sounds like you have something loading the engine when in reverse. Is your parking brake stuck on, or the rear brakes set up too high (assuming you have drum brakes in the rear)? Maybe the load is slowing the engine so much that the alternator's output drops too much as the engine speed drops. If this is the case though, you have an alternator that is about to leave you stranded soon anyway.

If the engine does not appear to be loaded abnormally in reverse, then inspect the back-up light circuit. Maybe you have a shorted bulb or socket that is overloading the alternator. However, if there were the case, I'd expect a fuse to blow, the headlights to cause the light to come on, and still would say that your alternator is weak.

Inspect the wiring in front of and behind your engine and transmission. Maybe when you shift into reverse the engine and transmission torque enough to contact a bare wire for the charging system, or cause a wiring harness to contact a grounded surface in the engine compartment.

I ran into this once on an old Taurus with the TBI 2.5L 4-cylinder (yes, I said old!). The car would stall when put in gear. This started shortly after a shop had replaced the transmission. They only did transmission work and stated that the transmission was not causing the stalling. They were semi correct. Dad and I found that idling in part, the fuel injector was working fine, but as soon as the car was shifted to drive, the fuel injector stopped pulsing. Tracing the wiring, I found a spot where the injector wiring ran near the joint where the transmission and engine bolted together. The wiring harness was crushed there, but not currently pinched between the transmission and the engine. However, the wires inside were sufficiently crushed and the insulation split. When the engine was shifted out of park, the engine would torque and the wires in the loom would short out. I repaired the wires and the car ran fine again.

-Rod