Wait light on with battery disconnected

[NVAM998]

New to me M998. Thought I'd put in a keyed ignition switch. Disconnected the neg rear batt terminal to the chassis for safety. Wired in the new switch. Turned it to the on position before putting it in the dash and the brake and wait lights came on. Wow, but I'm a newbie to the vehicle . So I disconnected the most positive lead on the front battery. Lights come on, but I don't hear the solenoid click. Very strange. Previous owner had a siren and lights attached to the rear battery, but they were removed when I pulled the negative terminal. Is there some type of backup charge somewhere that would cause the lights to be powered even with main batteries disconnected? I installed the switch in the dash and it all works but I find this very strange and I'm hesitant to do much else until I can find out where the power is coming from.

Thanks for any help!

 

[Mogman]

Welcome to the SS forums!!

 

[TOBASH]

You have a second battery system or a capacitor or some type of hidden battery connection somewhere.

Look to see if the prior sirens and lights had a battery system

 

[Retiredwarhorses]

Get rid the POS keyed ignition…start with that.

 

[Mainsail]

New to me M998. Thought I'd put in a keyed ignition switch. Disconnected the neg rear batt terminal to the chassis for safety.

Did you verify no voltage before you started working? Only disconnecting one of the batteries might not be zero volts in your wiring?

 

[FlameRed]

I kind of had a similiar experience.

Being a newbie, I thought that disconnecting just the negative would totally kill power. Not so much! I had a shocking experience and learned to disconnect both the negative and the 24V terminals. I leave connected the terminals that go across the batteries.

I am not sure why both need to be disconnected, but I learned the hard way, as usual.

 

[NVAM998]

Yeah I'm going to have to take another look and make sure I remove all the 12 aftermarket stuff first.

 

[mgFray]

If you have the middle charge on the batteries, you need to always remove BOTH Negatives! Otherwise you can get "back" circuit through the front he battery.

Being a newbie, I thought that disconnecting just the negative would totally kill power. Not so much! I had a shocking experience and learned to disconnect both the negative and the 24V terminals. I leave connected the terminals that go across the batteries.

Pulling the Negative and front 24V should accomplish exactly the same thing. I always worry though pulling a positive that a tool could touch the ground and arc, less likely when putting only negative terminals...

 

[Mogman]

What RWH is saying without taking the time to explain is that very few keyed switches and certainly the ones for sale on the popular web sites will not take the load presented by a HMMWV. They are very problematic in most cases and in some cases will cause catastrophic failures including fires

 

[NVAM998]

Still have the keyed ignition (gonna get to that) but swapped batteries and cleaned all battery connections and cables. My voltage gauge used to jump all around especially when cold but now it is rock solid center green. I've read that the bouncing gauge is the glow plugs but now I'm not sure. Used to also make a buzzing noise when bouncing, but that is gone. I did remove all the single battery 12 V wiring as well so maybe that played a factor.

Fuel gauge still jumps all around. Maybe a bad connection? I fueled up and it changed from mid range bouncing to pegged far right to "F" bouncing.

 

[TOBASH]

Bouncing gauge had to do with the old style protective control boxes. Some people called it afterglow. The glow plugs would continue to get electricity periodically in order to help the engine warm up while running. Then it would stop. That has nothing to do with your current Battery issues

 

[NVAM998]

Well I guess I wasn't paying attention - the voltage gauge still bounces when cold. Fuel gauge bounces too. Took it on the road to the dump - first time on pavement. Seems to wanter around on the road a bit above 40 mph. Semi's blowing by at 55 in the other direction is interesting with no doors. At least it has an attention getting beep beep horn.

 

[peggrw]

Well I guess I wasn't paying attention - the voltage gauge still bounces when cold. Fuel gauge bounces too. Took it on the road to the dump - first time on pavement. Seems to wanter around on the road a bit above 40 mph. Semi's blowing by at 55 in the other direction is interesting with no doors. At least it has an attention getting beep beep horn.

My fuel gauge sometimes sticks at full, sometimes reads correctly, and often just reads high or bounces around as the fuel sloshes inside the tank. Obviously a bad fuel sending unit. I need to get the initiative to drop the tank a little, cut a fuel sender access panel in the bed, since mine does not have one, and replace the sender with the new style. Your issue is also likely the fuel float sending unit in the tank. Depending on whether your HMMWV received the access panel maintenance kit it could be an easy diagnosis and fix. Otherwise you would need to drop the tank to get access. As far as the voltage gauge bouncing when cold... Normal operation is for the voltage to drop to the low yellow range for about 7 seconds when switch is first placed in run, back to the green, and then drops back into the yellow for about 2 seconds every 12 seconds or so for the first minute or two. But your post sounds like you may be describing something different than the normal Glowplug afterglow cycling.