Parasitic Draw - Electrical gurus?
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Tuned
Joined: Aug 2018
Posts: 367
Likes: 38
Parasitic Draw - Electrical gurus?
I am looking at a parasitic draw. 1999.5 F350 7.3 lariat
After all the modules, etc go to sleep. I am seeing the following:
117 milliamps
Pulled all fuses inside the cab:
Fuse 1 - flasher relay 5 milliamps
Fuse 2 - PCM 2 milliamps
Fuse 15 GEM, Brake Pedal Position 8-9 milliamps. Is this normal or too much?
Then pulled all the fuses/MaxiFuses in the Power Distribution Center under the hood
Fuse 18 - Power seat 33 milliamps
Fuse 20 - Ignition Switch B4 and B5 46 milliamps
Fuse 29 - Radio 12 milliamps
Fuse 18 - I have seats from a different vehicle installed. Not sure why it is sucking so much power when not being used, but I will have to investigate.
Fuse 20 - This seems like a lot. Why is this sucking up so much power? Is it possible that various aftermarket items are wired into this circuit and sucking power? Reverse camera, Alarm system, remote start, can't think of anything else.
Fuse 29 - seems like a lot for an aftermarket radio. I believe the radio has some function where it is in standby mode for a day, then goes into a deep sleep which I assume uses less power.
If I can figure out the power seats and ignition switch I think my numbers will be in a good range.
After all the modules, etc go to sleep. I am seeing the following:
117 milliamps
Pulled all fuses inside the cab:
Fuse 1 - flasher relay 5 milliamps
Fuse 2 - PCM 2 milliamps
Fuse 15 GEM, Brake Pedal Position 8-9 milliamps. Is this normal or too much?
Then pulled all the fuses/MaxiFuses in the Power Distribution Center under the hood
Fuse 18 - Power seat 33 milliamps
Fuse 20 - Ignition Switch B4 and B5 46 milliamps
Fuse 29 - Radio 12 milliamps
Fuse 18 - I have seats from a different vehicle installed. Not sure why it is sucking so much power when not being used, but I will have to investigate.
Fuse 20 - This seems like a lot. Why is this sucking up so much power? Is it possible that various aftermarket items are wired into this circuit and sucking power? Reverse camera, Alarm system, remote start, can't think of anything else.
Fuse 29 - seems like a lot for an aftermarket radio. I believe the radio has some function where it is in standby mode for a day, then goes into a deep sleep which I assume uses less power.
If I can figure out the power seats and ignition switch I think my numbers will be in a good range.
Laughing Gas
Joined: Feb 2014
Posts: 815
Likes: 296
From: KY
Its 50mA is considered normal by todays electronic vehicles. Your 100% sure you havent woke up the BCM when checking. Sitting idle the seat pulls 65% of your normal max? that dont seem right, Why do it even pull anything Id be wondering.
Laughing Gas
Joined: Nov 2020
Posts: 994
Likes: 367
From: Republic of Texas
My first look would be the alternator...
Pull the main feed and put the meter there on the main feed and the alternator lug. That diode tends to go bad and will be a draw point.
Truck asleep of course.
Also pull the hood lamp.
Pull the main feed and put the meter there on the main feed and the alternator lug. That diode tends to go bad and will be a draw point.
Truck asleep of course.
Also pull the hood lamp.
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Tuned
Joined: Aug 2018
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Seats are from a 2022 Grand Cherokee. There is a crazy amount of wiring on it. There are numerous modules on it for memory of seat position etc. It could be in the Cherokee these modules are forced to sleep -not sure.
To make sure that reading is correct, I will run the parasitic drain test again and this time once all is asleep I will disconnect the seat connection from the truck. If the reduction in milliamps is the same then that will confirm. Looking at the truck wiring diagram the seats look to be the only thing in that circuit.
The seats are easy to confirm and I can put a main switch on it if needed.
The ignition circuit is a bit more complicated, at least in my head.
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Tuned
Joined: Aug 2018
Posts: 367
Likes: 38
I was able to get down below 50 milliamps with the alternator connected. How can the alternator be an issue?
Hood lamp was removed for testing.
Laughing Gas
Joined: Feb 2014
Posts: 815
Likes: 296
From: KY
When I read jeep cherokee I cringed. After 15 jeeps, two of them GC's, I will say NOTHING Ive ever owned were more electrically problematic that those 2 GC's. Problem #1, parasitic draw from junk switches and sensors. Unplug 100% of the power to the seat and see what you get.
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Tuned
Joined: Aug 2018
Posts: 367
Likes: 38
When I read jeep cherokee I cringed. After 15 jeeps, two of them GC's, I will say NOTHING Ive ever owned were more electrically problematic that those 2 GC's. Problem #1, parasitic draw from junk switches and sensors. Unplug 100% of the power to the seat and see what you get.
Unplugging the seats = 32 milliamps. About the same as pulling the maxi fuse. The seats have lots of modules and wiring (heated, ventilated, 16 way power adjust with memory and massage).
I can install a main switch to shut off the seats. Or I can simply unplug them if the truck is going to sit for a long time.
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Tuned
Joined: Aug 2018
Posts: 367
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When I read jeep cherokee I cringed. After 15 jeeps, two of them GC's, I will say NOTHING Ive ever owned were more electrically problematic that those 2 GC's. Problem #1, parasitic draw from junk switches and sensors. Unplug 100% of the power to the seat and see what you get.
Unplugging the seats = 32 milliamps. About the same as pulling the maxi fuse. The seats have lots of modules and wiring (heated, ventilated, 16 way power adjust with memory and massage).
I can install a main switch to shut off the seats. Or I can simply unplug them if the truck is going to sit for a long time.
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5th Wheeling
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I'd place a modest wager( GEM box) is toast.It starts to fail it will do all kinds of screwy stuff, Including drain the battery.Being a 99 this is a clear indication its jacked up.Even though the 98 f250 I fixed( Gem box) had zero water intrusion, or blemishes on the board,it was done.As soon as I replaced Radio worked,4x4,no batt drain, or stuff coming ON Key not even in the ignition.Takes maybe 30 minutes to swap, Easy it really is.
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Tuned
Joined: Aug 2018
Posts: 367
Likes: 38
I'd place a modest wager( GEM box) is toast.It starts to fail it will do all kinds of screwy stuff, Including drain the battery.Being a 99 this is a clear indication its jacked up.Even though the 98 f250 I fixed( Gem box) had zero water intrusion, or blemishes on the board,it was done.As soon as I replaced Radio worked,4x4,no batt drain, or stuff coming ON Key not even in the ignition.Takes maybe 30 minutes to swap, Easy it really is.
Laughing Gas
Joined: Feb 2014
Posts: 815
Likes: 296
From: KY
Id google jeep GC seat causing parasitic draw. Its likely no uncommon and you may find its one specific part causing the issues. On either of my CG's it was sensors in the hatch where there are IIRC, 5-7 different sensors which caused the BCM to not be able to go to sleep. The battery would be dead after a few days or barely cranking after 2 days.
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