Unusual battery drain problem
Thread Starter
Heel & Toe
Joined: Apr 2022
Posts: 15
Likes: 4
Unusual battery drain problem
'85 C4 has parasitic battery draw, killing the battery.
I have found that the 15 Amp fuse for the 'CTSY/CLK is the problem. Engine off, lights off, doors closed, rear hatch down. All the obvious culprits.
I have hooked up my Fluke DVM (20 AMP DC scale) in series with the battery NEG & engine ground point, and with the 15 A fuse out, I get a draw of around 40 mA - very good.
When I put the fuse back in & measure I get around 5 Amp, for around 5 seconds, then current drops back down to the 40 mA for around 15 seconds, than back to the 5 Amp draw, repeating this cycle as long as I have the 15 A fuse installed.
My factory FSM manual shows that the the Hot At All Times distribution goes to Splice Point S240, which goes to 12 different elements.
When the fuse is installed, none of the lights are on, so I am in need of suggestions on how to find my problem.
I have found that the 15 Amp fuse for the 'CTSY/CLK is the problem. Engine off, lights off, doors closed, rear hatch down. All the obvious culprits.
I have hooked up my Fluke DVM (20 AMP DC scale) in series with the battery NEG & engine ground point, and with the 15 A fuse out, I get a draw of around 40 mA - very good.
When I put the fuse back in & measure I get around 5 Amp, for around 5 seconds, then current drops back down to the 40 mA for around 15 seconds, than back to the 5 Amp draw, repeating this cycle as long as I have the 15 A fuse installed.
My factory FSM manual shows that the the Hot At All Times distribution goes to Splice Point S240, which goes to 12 different elements.
When the fuse is installed, none of the lights are on, so I am in need of suggestions on how to find my problem.
Melting Slicks
Joined: Nov 2016
Posts: 2,256
Likes: 3,083
From: So Cal
2023 C4 of the Year Finalist - Unmodified
The only guess I have is that it has something to do with the power antenna which can draw 5 amps if locked-rotor. The schematics don't show a thermal breaker in the motor, but many motors have them. If the limit switches in the antenna motor aren't opening at the end of travel, the motor will continue to draw current until the thermal breaker (again, IF it has one) opens. Thus your cycling 5 amp draw.
The antenna relay is under the trim at the very rear of the cargo area. 6 wires in two connectors of 3 wires each. Unplug the connector with green, gray and white. Those go to the antenna motor. See if the draw ceases.
The antenna relay is under the trim at the very rear of the cargo area. 6 wires in two connectors of 3 wires each. Unplug the connector with green, gray and white. Those go to the antenna motor. See if the draw ceases.
Thread Starter
Heel & Toe
Joined: Apr 2022
Posts: 15
Likes: 4
Got it fixed!
The car had a Pioneer radio installed when I bought it. The kind with the removable face plate/control panel.
That panel looked like it was partially out, so I pop'ed it back in, turned it on, listened to some FM, antenna going up.
Turned it off, antenna went all the way back down,and with doors closed, no lights, etc, the current draw was back down to 10 mA.
All is right with the world.
That panel looked like it was partially out, so I pop'ed it back in, turned it on, listened to some FM, antenna going up.
Turned it off, antenna went all the way back down,and with doors closed, no lights, etc, the current draw was back down to 10 mA.
All is right with the world.
