Hi all, have a problem with ~3.2A draw on the car. I'm hoping I'm overlooking or doing something stupid. I have been pouring over the FSM trying to narrow this down, but the diagrams I've found so far have been lacking in clarity. Been trying to figure out what is actually always hot, isn't the starter or alternator, and doesn't go through the junction box and now at the point of just asking for help.

Current status with 3.2A draw remaining:
All fuses from box removed
Starter fully disconnected from power (and now in need of repair...stud for purple wire decided to strip internal to the starter before the nut let loose, had to remove the wire from the terminal)
Positive battery cable removed from junction box
Alternator disconnected
Radio removed (More on that later)

Tests performed:
Fuse by fuse removal
Draw test of relays one at a time and then replacement (except the 2 above the junction box)

Method of testing current draw:
Negative cable disconnected from battery, multimeter between battery and cable.

How the issue was identified, a note on the radio, and general musing:
Since I bought the car it had a Sony radio that received power but did not work. I recently purchased a Pioneer unit from crutchfield. Wired it in. Went to put the car in A/C and....nothing. All lights interior lights barely illuminating. I thought, weird, I drove it extensively less than a week prior and the battery is relatively new (<1 year). Threw it on the charger came back 2 hours later and was able to fully verify radio operability. It even tried to raise the power antenna (which someone forcibly removed at some point...how nice of them). Anyway, I left it on the charger all night so I could drive it to work in the morning. Walk out, charger says battery is green. Key in ignition, turn, and a single click with no attempt to start. That's when I tested the current draw and found the problem of ~3.6A draw with all fuses and connections still installed. Started working backwards, first removing the radio. Then went fuse by fuse. Then hit the relays I could find, and reconnected them. Then finally ripped every single fuse out. Then removed power from the junction block. Finally jacked passenger side up and removed power from the starter (and gave myself something new to fix). I had first thought maybe I messed something up with the radio, then I thought it has to be the starter, now I'm unsure. I see that the light switch is supposedly always hot, same for the ECM, but not sure what else.

Details about car that may or may not be relevant:
1989 z51 ZF6
VATS has been disabled on this car for years

 

Just a guess, is there a courtesy light delay module that's not timing out? Once you turn everything off, collapse the door switch, and wait about a minute to see if it powers down.

 

Apologies if the picture at the end is gigantic, just snapped quick on the phone 1 minute ago. Disconnecting the power connector closest to the battery has removed the drain...off to the FSM to figure out what it is for

 

If the fuse is out, it's not getting power

 

Another level of detail, draw is 0.0. Looking at the FSM battery section i think the connector is the “engine connector” per the below figure, but I’m not certain.

 

Why don't you just follow that wire to see where it goes? Shorts are a pain, but it takes a step by step approach,.

 

Thats the tomorrow plan pending any other feedback. I'm concerned its less a short and more something that's failed. I don't know how much is on the other end of that wire, but I soon will. My gut says the ECM is on the other end, but my gut is also an idiot that I should never trust.

 

Thanks. To be clear, the headlight doors are hot at all times and through the junction block? I currently have the junction block removed from power so I'm not sure that would be it, if so.

 

Managed to eliminate the ECM. Pulled the plastic panel down on the passenger side, removed ECM, and then the harness from the ECM. Reconnected the link mentioned above, current draw still there.

Aside from the headlight switch, I’m not sure whats left. Have more reading the FSM, but hopefully one if you who has more knowledge and has spent more time playing this game can provide insight in the meantime.

 

You said you removed all the fuses, did you also remove the circuit breakers from the fuse panel? Once I pulled all the fuses and and I forgot to pull the circuit breakers. Turned out to be the power seat circuit which is on a circuit breaker.

 

I did. Theres nothing in the panel right now.

Another minor update. I have checked the current with the oil pressure sender/switch, fuel pump relay, and both MAF relays individually removed. Still 3.2A draw.

At this point I’m lost and will need to sleep on it/wait for more guidance. Power distribution diagram has has following connections out of battery:

1. Power to the items in my last paragraph which are all theoretically checked and eliminated. (Fusible link H)
2. Power to junction block. Disconnected and should eliminate fuse panel, headlight control unit, modulator valve, ignition switch, and light switch
3. Power to (from) alternator, which is disconnected from all connectors.-edit: whoops, this should be through junction block too
4. Power to starter, which has all connections removed, and should thus take out the AC (connected to same post as starter power in wiring diagram)

 

Where does the alarm get its voltage from?

 

According to what I’ve seen in the FSM, it should all be through the fuse panel. Anti-theft and alarm relies on several fuses.

 

Bumping this up. No update as I haven't been able to work at it the past few days.
I have been looking through the FSM to try and identify what could possibly be the cause, but haven't come up with anything given what I've checked out so far.

At this point I'm hoping one of y'all that are more versed in these/more experienced in troubleshooting can provide insight. As of now, my only idea is to put everything back together and start over from scratch.