Anti-theft red light on solid when key off

So that’s 5.9 mA?

 

I think so but set your meter to the 10A scale and make sure.

 

Maybe I need a lesson with the DMM. I thought the 200mA port was for reading up to 200mA and the 10A port was for measuring bigger draws up to 10 A. But you’re saying put the dial on 200mA and put the lead in the 10A.

 

On the 10A scale I get 0.54

 

Meters tend to vary in that regard, most do 10A though so I always use that setting.

So it looks like you have about half an amp or 540mA

 

Yes. And you’re saying that’s waaaaaay more than I should have.

 

Yea that's more than a bulb but give a few min and see if it drops, I just checked mine and it takes about 2 min to drop below 100mA.

 

Ok. I may get a new multimeter too. See if it’s different. This things been around the block over 25 years. Any initial thoughts on what fuse I could pull that would pull that kind of draw? Tying to avoid pulling each and every one.

 

You can try the ECU-B first but beyond that a better way is to check voltage drop on each fuse.
The best way to do that is set your meter and leads to volts DC on the lowest scale (so 2v on yours) and put the leads across the 2 teat terminals on the fuse, if it doesnt read 0 there is current going through the fuse if that makes sense.

 

Took reading when removed the ECU-B fuse and it dropped almost in half. But that would still leave a pretty significant draw still in addition. when you say check voltage across the fuse, do you mean the fuse itself, or pull the fuse out and test the socket?

 

Sorry. I know it the Fourth of July. I’ll do some more poking around. And get back with you after the weekend. I’m going to get a new multimeter. I feel like the battery wouldn’t last the night at a 500mA drain. And it lasted a little over 24 hours and started strong. I don’t want to take up any more of your holiday. Thanks again!

 

You test across the test terminals on the fuse with it installed.

 

All good, I'm working anyway just not at the shop but I'm on a farm and there's always stuff to fix here.

Half an amp probably wouldn't kill a good battery overnight but it certainly would after a day or two.

 

I never even knew those were there

 

Yea all blade style fuses have test points.

 

Ok. So wasn’t DMM ‍♂️. But you got me onto something. The only two fuses (at least the plug ones…I didn’t mess with the big blocky ones), I get approx 500 mA when testing parasitic in series with terminal and cable. When I remove the ECU-B fuse it cuts it in half. When I further remove the ALT-S fuse it goes to 30 ma. I found the ALT-s fuse and ECU-B fuse reading around 2.3 millivolts with the fuse test you had me do.

 

What is the ALT-S fuse to?

 

So the alternator is pooched and we have at least one other module staying awake.

 

If you say Alternator…hers an interesting bit of info..before I picked this truck up from the guy I bought it from…he had to out a new alternator in it. Coincidence? If that’s even what ALT is.

 

Alternator voltage sense, it only feeds the regulator in the alternator so I guess the regulator got fried. You can put the fuse back in and unplug the alternator to confirm.