Batteries reversal Mishap

[4x4nutz]

Got a call this morning that a client had accidentally reversed the batteries. The glow plug unit was not damaged and it still starts, but none of the lights work. Before I make the 100+ miles round trip to diagnose and repair the problem, what can I expect the damage to be? I am taking another light switch box with me, but I am wondering if maybe all the lights might have burnt out when the batteries were reversed by accident, and wouldn't the light switch have to have to been on during this screw up to burn them out? Anyway, I appreciate the help.

 

[papakb]

Something you need to add when making a post like this is the year and model of your truck. Over the years things changed in their design and it's helpful to know what you're working with. Did they attempt to start the truck after the battery installation? Does it still drive or did the TCM (if installed) still work? More information is needed to effectively help you.

Yes, the main 3 lever light switch would have to have been on to cause a problem but if you have the worthless push button troublemaker it's anybodies guess what may have happened.

LED lights are the only ones that care about polarity but since there semiconductor diodes they just won't work with the batteries installed backwards. They come back to life when the error is corrected. Incandescent lights don't care what polarity they see and will work either way.

Now the early control boxes had a reverse polarity disconnect in them that might have failed with the batteries installed backwards but usually that takes out the whole control box. Do you know which one you have installed?

 

[Milcommoguy]

What kind of light. LED or incandescent?

Not a bright connection, CAMO

 

[TOBASH]

manual or pushbutton light control box? New owner? Did they forget to turn the manual light control on?

Ask simple stuff prior to the drive.

 

[Mogman]

The first thing I would check is the charging voltage, if he has a 200A alt they do not like to be connected backwards.
I suppose it would be possible the alt is running WFO and burned out the lights, as others have said if it has a push button light switch that could be the issue.
The light switch gets its power from basically the same source as the run switch

 

[papakb]

That all goes back to the basic question: What are we working with?

 

[Retiredwarhorses]

You can fry just about anything if it’s plugged in…just because the switch isn’t on, does mean it can’t melt the switch, voltage is present in the switch. When saying he wired the batteries backwards, that means he sent positive voltage to all grounds….at least to me it does, and if that’s the case, it can be a mess.

 

[4x4nutz]

Something you need to add when making a post like this is the year and model of your truck. Over the years things changed in their design and it's helpful to know what you're working with. Did they attempt to start the truck after the battery installation? Does it still drive or did the TCM (if installed) still work? More information is needed to effectively help you.

Yes, the main 3 lever light switch would have to have been on to cause a problem but if you have the worthless push button troublemaker it's anybodies guess what may have happened.

LED lights are the only ones that care about polarity but since there semiconductor diodes they just won't work with the batteries installed backwards. They come back to life when the error is corrected. Incandescent lights don't care what polarity they see and will work either way.

Now the early control boxes had a reverse polarity disconnect in them that might have failed with the batteries installed backwards but usually that takes out the whole control box. Do you know which one you have installed?

 

[4x4nutz]

Thank you for the reply. 2002 1123 with 200amp gen, three toggle arm light switch. Truck still starts and runs and gen is charging. Lol...I have actually been on the receiving end of a push button light switch fire. It was like a fireworks show, but the rest of the 1097 survived.

 

[papakb]

The standard 3 lever light switch has a circuit breaker in it that might have bit the bullet and your spare might be all you need. That and a multimeter should get you going again.