Crazy Instrument backfeed and parasitc draw

[SRQYukon]

I know there are several discussions on parasitic draw issues, but none of these seem to describe what's happening to my '03 Yukon. For a couple of weeks I have had a parasitic drain that is caused by things that won't shut down when the ignition is off. For example when I turn off the ignition, the backup camera, the A/C fan motor and an array of warning lights in the instrument cluster stay on (check engine, ABS, and others). Also many thing should have power with the ignition "Off" don't work such and the power windows and door locks. Additionally, when the ignition is "on" there are no working gauges (fuel reads empty and no oil pressure or battery gauge). The speedo and Tach still work but again all of the idiot lights are on. The battery was draining overnight, so initially I disconnected the battery. After a couple of days, I jumped the truck and everything worked fine for about wo days. then everything started all over again. I teh decide to connect my Launch scanner to the OBDII port to see if there were any codes. There is no power to the OBDII port!. I researched that, and everything I found says its a blown fuse. I literally checked every fuse and nothing is blown in either fuse block. I eventually pulled two fuses (radio and SEO B1) and thought that had stopped the draw. However, after sitting for three days the battery was again drained. So I basically just slowed the draw by removing some of the higher amperage items that were remaining "on". I know the instrument cluster can cause some of these issues, but mine was rebuilt less than two years ago. I've contemplated calling up Circuit Board Medics and asking about the issue, but I'm pretty sure thay will deny that its anything to do with their work. In past 2-3 years I've replace the master power door/window switch and the headlamp switch, but no problems with either. I also had to replace the backup camera a few months ago, but the head unit has been in there for 5 or 6 years. I did have the Fleece 4-Hi mod installed but removed it with no change in the behavior. So it feels like I'm looking for a needle in a haystack. Anyway, there is no need to repost suggestions that have appeared in previous discussions about parasitic draw (silver migration, PCM corrosion, ABS connections, etc). I have read those prior to posting this. I'm just wondering two things:
Has anyone else seen this specific type of issue and, if so, were you able to determine what cauesed it?
Is there a specific relay or some interrelated circuitry that connects these issues together?

 

[Petersnow]

Hi,

My 2005 Denali is draining battery power from quite some time, but no lights are on with ignition off, which is your case. The panel gauges sometimes do no work quite well with bad readings (temperature, fuel, battery voltage), but right now everything is working fine since replacing the battery with a Optima Yellow Top because of my audio system. Some people had told me that the HID ballasts are causing the dead or very weak battery in two days, need to verify that in more detail. Other than that, I need to turn it on 2 times a day if I don`t use it daily.

Regards

 

[Fless]

There are many good YouTube videos on parasitic draw (South Main Auto, for one); if you haven't tried the "voltage drop across the fuse test points" I would highly recommend it. Also, interrupt the negative cable with an ammeter and watch the draw as the modules go to sleep (or don't go, as the case may be). Be careful about not starting the truck or using accessories with high loads -- the ammeter needs to be capable of handling the current. Your target draw asleep should be under 50 millivolts (0.050 v) and will probably drop to 30 mv or less if all is well.

For the voltage drop measurements you'll need a chart showing the calculated amp draw based on the fuse style and size. Shout if you need a link to those charts. Pay particular attention to the IPC/DIC, PCM 1 and PCM 2 fuses circled below, but check all of them that have the test points.



If either of the PCM fuses show current draw while the truck is asleep, pull the PCM connectors and check for water migration. Also clean with DeOxit or similar if you have some.

If you have the AUTO HVAC head it can take 3 or 4 hours to fully go to sleep. Also know that the main battery cables can rot out from the inside and not show that on the jacket, so they may need to be tested.

 

[SRQYukon]

Sorry, it was the radio and cig lighter fuses that I removed. I don't have HID headlight, so that isn.t my issue.

 

[SRQYukon]

There are many good YouTube videos on parasitic draw (South Main Auto, for one); if you haven't tried the "voltage drop across the fuse test points" I would highly recommend it. Also, interrupt the negative cable with an ammeter and watch the draw as the modules go to sleep (or don't go, as the case may be). Be careful about not starting the truck or using accessories with high loads -- the ammeter needs to be capable of handling the current. Your target draw asleep should be under 50 millivolts (0.050 v) and will probably drop to 30 mv or less if all is well.

For the voltage drop measurements you'll need a chart showing the calculated amp draw based on the fuse style and size. Shout if you need a link to those charts. Pay particular attention to the IPC/DIC, PCM 1 and PCM 2 fuses circled below, but check all of them that have the test points.

View attachment 376568

If either of the PCM fuses show current draw while the truck is asleep, pull the PCM connectors and check for water migration. Also clean with DeOxit or similar if you have some.

If you have the AUTO HVAC head it can take 3 or 4 hours to fully go to sleep. Also know that the main battery cables can rot out from the inside and not show that on the jacket, so they may need to be tested.

Thanks, Fless. I'll have to round up my ammeter and see what it tells me.

 

[SRQYukon]

Thanks, Fless. I'll have to round up my ammeter and see what it tells me.

I think we've traced it to the PAC Audio interface for the head unit. Still trying to rule out the head unit itself.

 

[Fless]

I think we've traced it to the PAC Audio interface for the head unit. Still trying to rule out the head unit itself.

I had to rule out my PAC interface when I was diagnosing my parasitic draw. If you're running the one listed below, this is what I got from the mfr.:

Jourdan Cherrier (AAMP Global) Dec 8, 2020, 14:52 EST Hi Steve, The RP5-GM11 should draw 13 milliamps or less at rest. Jourdan Cherrier Technical Support Specialist

 

[SRQYukon]

I had to rule out my PAC interface when I was diagnosing my parasitic draw. If you're running the one listed below, this is what I got from the mfr.:

Jourdan Cherrier (AAMP Global) Dec 8, 2020, 14:52 EST Hi Steve, The RP5-GM11 should draw 13 milliamps or less at rest. Jourdan Cherrier Technical Support Specialist

Yep. It's the same one. That info may help once I get my multimeter working. The battery leaked inside the meter. I'm trying to clean it up, but and I may have to replace it. I never remember to remove the batteries after use. It's nice that it uses AAAs, but they seem to leak way more often than the 9-volts that my Fluke tester uses. But the Fluke doesn't do DC current measurements. Thanks for the information. Oh. forgot to ask: Was the interface the cause of your parasitic draw, or something else?