This was a referral buy a long time client, 1994 C1500 with a "K" code TBI 5.7L/4L60E with 93,000 miles. Nice truck other than the sun beaten dash.
Complaint....Battery is completely flat after 5-6 days.
Knowing old retired folk like I do, I asked him about his driving habits. He goes to the Pharmacy then to the Grocery store once a week which is a one mile round trip with 3 engine starts. I advised that even if I do find a draw....The battery is going to get depleted anyway unless he take longer drives.
This truck has been to a couple local shops, One being a guy I've known for years & is pretty good with electrical.
Hooked up my Multimeter in series set on the 2 amp DC scale & had a 38mA draw, That's not much more than I'd like to see on a modern vehicle, But far more than this old truck should draw.
Whipped out the Thermal Imager just for experiment sake, Nothing. Pulled fuses one at a time...Nothing other than a the 5mA that the PCM drew.
Decided to separate the Body from the Underhood electrical buy unhooking the Bus Bar form the Battery.....Draw went to Zero. Meaning the draw was inside the cab NOT under the hood.
Unhooked the eyelets one at a time at the Bus Bar 'til the draw went to 5mA.
Left the offending circuit unhooked, Started the engine & proceeded to check what wasn't working. The Radio & HVAC Control Head were dead.
The HVAC Control Head was the easiest to unplug & ended up being the parasitic draw.
Had a used HVAC head stashed back.....With everything hooked up....
PCM, 5mA
Radio, 2mA
HVAC, 2mA
For a total of 9mA of parasitic draw.
Closing....The HVAC control head was drawing 29 milliamps more than it should've, Don't shrug off customer complaints!!
Complaint....Battery is completely flat after 5-6 days.
Knowing old retired folk like I do, I asked him about his driving habits. He goes to the Pharmacy then to the Grocery store once a week which is a one mile round trip with 3 engine starts. I advised that even if I do find a draw....The battery is going to get depleted anyway unless he take longer drives.
This truck has been to a couple local shops, One being a guy I've known for years & is pretty good with electrical.
Hooked up my Multimeter in series set on the 2 amp DC scale & had a 38mA draw, That's not much more than I'd like to see on a modern vehicle, But far more than this old truck should draw.
Whipped out the Thermal Imager just for experiment sake, Nothing. Pulled fuses one at a time...Nothing other than a the 5mA that the PCM drew.
Decided to separate the Body from the Underhood electrical buy unhooking the Bus Bar form the Battery.....Draw went to Zero. Meaning the draw was inside the cab NOT under the hood.
Unhooked the eyelets one at a time at the Bus Bar 'til the draw went to 5mA.
Left the offending circuit unhooked, Started the engine & proceeded to check what wasn't working. The Radio & HVAC Control Head were dead.
The HVAC Control Head was the easiest to unplug & ended up being the parasitic draw.
Had a used HVAC head stashed back.....With everything hooked up....
PCM, 5mA
Radio, 2mA
HVAC, 2mA
For a total of 9mA of parasitic draw.
Closing....The HVAC control head was drawing 29 milliamps more than it should've, Don't shrug off customer complaints!!
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