noticable voltage drop when shifting to reverse (1 Viewer)

[PHIL O]

hi mudders. was driving home last night when i noticed that each time i shift the hdj81 (auto tranny) into reverse, the voltage meter drops noticably. does shifting an auto tranny into reverse drain that much from the battery? i tested other accessories and the headlights too, but they dont bring the voltage meter down like the reverse. they dont even move the needle down on the voltage meter. is this an alternator issue?
hoping for your usual support fellow mudders.
hdj81 is stock. no accessories that go on with the reverse. just the light and the beeper.

 

[sailor]

If you still have the Japanese batteries, I'd replace 'em. I have group 27s.

 

[PHIL O]

i don't have the original batteries anymore sailor. these are batteries designed for the tropics and maintenance free. quite new. but if it were the batteries, shouldn't it drop the voltage too if i switched on the headlights?why could the voltage drop occur only when i hit the reverse?

 

[SeanAndHis80]

i don't have the original batteries anymore sailor. these are batteries designed for the tropics and maintenance free. quite new. but if it were the batteries, shouldn't it drop the voltage too if i switched on the headlights?why could the voltage drop occur only when i hit the reverse?

Do your reverse lights come on when you put it into reverse? Maybe throw an ammeter across the fuse for the reverse lights and see how much draw the circuit is using when the truck is in reverse. I bet you have some sort of short circuit there.

 

[Scamper]

I agree with Sean. My bet is that you have a short in the wiring that feeds the reverse lights in the back. For a simple test, just disconnect the fuse that powers the tail lights, then put it in reverse and see if the voltage drops as before. If it doesn't drop, then the short is in that circuit. I see that you're in a marine environment, so this would not necessarily be a big surprise after so many years...

 

[PHIL O]

thanks sean and scamper, that's what i suspected too. but the reverse light and backup beeper works just fine. might do the fuse off of reverse circuit test then if it doesn't drop, i'll confirm with a current test. this will surely save me some time on guesswork. anything i should know about the reverse circuit? i mean is it only the light (reverse and gear indicator) and beeper that is activated by the reverse switch? thanks a lot fellow mudders

 

[SeanAndHis80]

Is the beeper standard equipment in the Philippines? Is is not here in the States. ...Any non-Toyota part would be my first suspect.

 

[PHIL O]

it is stock on the japanese rigs. we imported this from japan and had it converted from right hand to left hand drive. everything else is stock. i had a peacecorp volunteer as a passenger once and he commented on the beeper. he said cars in the US dont have those fancy beepers.

 

[80t0ylc]

The beeper on my work rig was malfunctioning and I found a quick way to isolate it. Usually, there is only one wire (12V) to the beeper and return is through the mounting connection. Just remove mounting hardware and let it hang loose. This will temporarily break circuit. Start rig and try reverse. If voltage drop disappears, your problem is the beeper. If not it could be the wiring to the beeper or your backup light circuit. HTH

 

[z_power]

I also noticed this voltage drop; THINK it's a matter of where the V-meter is connected but i'm just to lazy to dig into diagrams... I think that voltmeter, backup lights, blinkers and a few others are connected "after" power relay and fed from the same thin wire, if relay contacts are old and worn then it adds some drop, too. Switching on any of these lights causes voltage drop in the whole section and also on a meter. Aux. lights are fed from another point therefore their influence on readings are less noticeable.

edit: connect an auxiliary voltmeter direct to battery and compare readings with in-dash one, this should let you (and us ) know some facts...

 

[Lka1988]

FWIW, I have a pretty good voltage drop in Reverse as well.

 

[lndcruz]

me to, not worried at all.

 

[Dave 2000]

My reversing lights have been replaced with 55w halogen bulbs which is great when reversing at night but this does bring down the volt meter a tad as would a pair of headlights. Has your car been converted with these?

regards

Dave

 

[PHIL O]

thanks fellow mudders.
looks like many of us guys experience the same voltage drop when reversing. maybe this wouldn't be too much of a worry then. i was just alarmed when i compared voltage drops when reversing and when headlights are switched on. and i noticed that reverse uses more current than the demanding headlights. my reverse lights are stock 20 watt bulbs. i have cleaned my relays too.