Good evening.
Electrical issues are my nightmare and my brain goes on strike every time I need to solve issues of that nature on cars.
I inherited a 99 Jimmy SLT that has been sitting over a year.
I do have a repair manual and have found an electrical diagram showing that this fuse powers :
- Radio
- Climate control module ( I believe I have the 'automatic' kind, whatever it means)
- Instrument cluster.

I have unplugged each one of the three, but the parasitic draw remained.

My question(s):
- Could the fuse power anything else I did not find on my diagram?
- Should I look for a short in the wiring, and if so:
- is there a likely spot where such an issue might appear?
- How would I check that ?

 

In modern vehicles, you have to maintain current to the vehicle while switching over power to going just through your meter. Each time the vehicle completely loses power, all bets are off for measuring parasitic draws until vehicle has been operated normally and all timers for this and that have expired. You will probably notice that the vehicle will draw over an amp when you first hook up the meter, and then it will settle to something lower during the first 5 minutes.

There are special tools required to do this conveniently.


So how much is your draw the way you are measuring? What is the reserve capacity of your battery? What is the fuse in question?

 

Thanks LesMeyer for answering.
Edit: Thanks for the link to those tools, they are new to me, but I don't own one, and did find the circuit causing the issue. Now I am trying to find the issue itself.

I glossed over a things I realize in hindsight I should have shared.
Vehicle history:
The PO sold the vehicle to me for a song because it had the following issues:
- Battery would die in 2 days or less. He had bought a new battery, but the issue remained.
- Engine started to stall without notice while driving but usually would start again after a few minutes, except the last time.Now the issue had graduated into a plain "crank but no start" problem.
.- 4WD switch not lighting on and 4WD unavailable.


The intermittent stall/ "crank but no start" happened to be the fuse ECM1 (feeds the pink wires to power both the ignition module and the coil) not being seated all the way in and not sending power to the ignition at times.
4WD: not touched that one yet, but I presumed it was linked to the parasitic draw. The vacuum lines are toast, and I now have a blown ATC fuse ( was fine when I got the vehicle and chased the draw the 1st time). to blow the ATC fuse, I suspect only the encoder motor could do that, but that is for later. ATC fuse blown and removed, 4WD fuse in the dash fuse box also removed, this issue should not impact the chase for the parasitic draw I am after.

For the (non 4WD related) parasitic draw:
I did 2 tests. both with the door switch in closed position (with a clamp and a small wooden block, like shown on the youtube videos).

Test #1: Done 3-4 days ago, and helped me to identify fuse #19 "RDO BATT" as my main culprit for the draw.
Meter in line on 10 amps, waited a while for draw to stabilize. I don't remember what the reading was exactly, but it stopped moving after a few minutes and It stayed constant during the whole test ( I had my son do the reading on the meter)
Draw flickered a few times as I removed the fuses, but nothing above 0.5 amps, so I let those slide. On the RDO BATT, the draw went down by over 1 amp, so I pulled the fuse out it and stopped there.

Test #2 (yesterday)
Battery hasn't drained during those 3-4 days, so I knew I had found the culprit. ( I know there may theoretically be more, but that one needs to be solved before I put my mind on anything else)
I had little time so I did not wait 10+ minutes for the amperage to go down to 0.1 amp or less that time, but I did wait for the current draw to stop moving. It stabilized around 2.4 amps after a minute or two and I did my test (with my son again) at that point. In between each test as well as at the end, we checked the draw and it came back to 2.4 amps every time, so I used that as my "base" draw to compare everything to.

What I did:
- Dash front cover removed, radio, A/C and instrument panel unscrewed but connected to the wiring harness.
- Fuse #19 still removed. door switch closed with clamp.
- Test Battery at 12.6 V. Marvel at that nice number on the screen for a few seconds.
- Plug in meter on 10 Amps reading.
- Key on.
- Once stabilized to 2.4 amps, plug in fuse #19, and check current draw. 1.1 additional amp draw measured for a total of 3.5 amps drawn.
- Remove fuse #19. draw goes back to 2.3/ 2.4 amps.
- Remove radio connector. plug in fuse#19. The 1.1A parasitic draw comes back. Unplug fuse #19. back to 2.4 A draw on the meter.
- Plug radio back in, unplug A/C control module. Plug in fuse #19. Draw comes back. Unplug fuse #19. back to 2.4 A draw on the meter.
- Plug A/C back in, unplug instrument panel connector on top (which I was convinced was the culprit, after reading so many posts about that fuse). Plug back fuse #19. Draw comes back. Now I'm stumped.
- Remove fuse #19. keep instrument cluster disconnected. disconnect radio also. disconnect A/C module also. put fuse back. parasitic draw comes back.
- Getting tired of things getting more complicated than they need to be. I remove the fuse, remove the clamp, close the vehicle and go do something else.
- After a few hours, I decide to post on the forum for advice.

I tied to redo the test later yesterday night to check if I would get a different result, but I was tired: I tried with the red connector back on volts/mA and not the 10A plug, and fried the fuse on my meter. I ordered new fuses online (the ones needed are not available in my neck of the woods) and another meter, for good measure. Those will come in next week.

 

Do you have the factory repair manual including the electrical wiring & diagrams or just a Chilton or Haynes?

 

I did get something in between. I purchased a manual from an online website RepairnManualNow that offers a one size fits all repair manual to download with schematics, diagrams etc. The manual I have is not well organized, but for the price I paid, it beats Haynes by orders of magnitude regarding details and content.

 

Over in the Avalanche forum I have heard that the instrument cluster is something that initially draws a fair amount of current but goes to sleep and is a common problem with parasitic draws when it doesn't fall asleep.

Because of the cost involved, I would absolutely make sure you are allowing it the chance to fall asleep before replacing it. This will require the special tools and a special sequence of checking. Just know that instrument cluster draw stays high before going to sleep. You need to do the testing correctly an make sure that the cluster is NOT falling asleep after say 10 minutes or so. This means that you install the battery disconnect, drive the vehicle, and put your meter in series before turning the **** and making all the current go through your meter. Then you need to wait for some time before seeing what the parasitic draw is. This is absolutely done with the Key OFF.

I'll take a look and see what else is on that circuit for you.

Here is the main one that has all the things that are on fuse 19

 

Here's some more that include parts of the fuse 19 circuitry, but generally more detailed.

...... and finally a bulletin and the actual factory procedure for parasitic draw testing.

So read all this stuff carefully (especially section 12 of the parasitic draw testing) and if you don't understand then ask.

Finally, know that there are trouble codes that set in the PCM that are not part of the powertrain codes typically discussed and these will not turn on the SES light or turn up in a typical cheapo scanner. If you have a capable scanner, you can read ALL the codes, and there might be some help there. Part of these codes are problems with class 2 communication between modules that typically cause parasitic draws. A cheap scanner that will read everything is Car Gauge Pro for Android and a bluetooth OBD2 device.

Now you should have everything that you need.

 

Thanks a lot!
I will check everything.
My main area for confusion is that the parasitic draw on the RDO BATT fuse remained after I removed Instrument cluster, radio and A/C module altogether. I do not see why I should keep testing radio, instrument cluster, and A/C for that draw at this point. What am I missing?

In the diagrams you gave me, there is mention of a "power distribution cell 10" in the circuit down the fuse, my guess is that this is the junction in the harness directing power to radio, A/C, and instrument panel. Please correct me if I am wrong in that assumption.

 

Like I said before, everything on fuse 19 is in the RDOBatt schematic. In the other schematics you will find more detail for certain systems, but they do not have all systems on that fuse shown. Cell 10 is a generic name for what is covered in other schematics.

IMHO you need to stop and forget about everything what you have done so far because you clearly did not check for a parasitic draw correctly. Did you read the procedure (especially section 12)?

We need to establish if you really have a parasitic draw on fuse 19, or if you are mistaking a normal timed draw for a parasitic draw. I believe this is why nothing is making sense to you. Hook everything back up, get the test equipment that you need, follow the parasitic draw procedure exactly, and let things time out and go to sleep for the 20 minutes. Then come back with your readings after various times and also find out the reserve capacity of your battery (forget unplugging things at this point) - and I will help you. If you have questions about doing the test correctly, please ask. One thing of particular note is that when you open the door to mess with the fuses, you wake up the modules on the vehicle LAN and that itself causes some draw - so you can't mess with anything during the 20 minutes.

I'm trying, but you're going to have to stop and listen to me - and then do your part.

p.s. do you have a remote audio player like a CD changer or tape deck? It would be on this circuit.

 

I understand: my method to find the draw is not the proper way to do it and provides unreliable or downright wrong results. I'll do a better check when the parcel arrive.
I still don't understand why I would sense an amperage increase (parasitic or not) when inserting back that fuse if everything is disconnected down the line, though. this bugs me, as the situation was repeatable and the draw the same, as mentioned in previous posts.