I have a 2010 3.5L V6 charger that I have owned since 2011 and driven 90,000 miles without an issue - until now.

About a month ago I went out start the car in the morning and was unable to unlock the car as the battery was dead, so got AAA out to jump start the car.

The next morning the same thing happened and since the car was 6 years old decided that the battery was probably due a change, so changed it without any diagnosis.

That seemed to fix the problem but a week later I came out to start the car and the battery was dead. After jump starting and leaving the car to charge the battery I then took the car to O'Reilly's to have the battery and charging system tested. They confirmed the new battery was good but diagnosed a faulty (shorted) diode in the regulator that was draining the battery whilst the car was parked. To solve this they sold me an alternator but when I got home and got the new alternator out of the box it had a label stating that the regulator was external to the alternator, so I took it back and did a little research, which revealed that the regulator for the Charger is in the PCM. I also confirmed that there was a 1.8 Amp draw on the battery when the car was parked (even with the trunk light removed). I tried pulling every fuse and relay in the trunk and under the hood in turn to isolate the circuit responsible for the draw but none of them reduced it, so I bought a new PCM and got the dealer to flash it at a total cost of about $450. In the meantime I installed a battery isolator so that my Wife could disconnect the battery when she finished driving the car each day whilst I was a away on business.

Once I got back I fitted the new PCM and removed the battery isolator. Everything was OK for a week until the battery drained again! After kicking myself for not testing the drain after fitting the new PCM I decided that it would be best to use the expertise and access to technical data of the dealership to diagnose the problem, which cost me a further $320.

Their recommendation is to replace the alternator and instrument cluster but I have no real confidence in the diagnosis and wonder if anybody else out there has similar experience or is able to offer help.

The write-up from the dealer states "Checked for excessive draw per customer request - found intermittent spike in draw from 10mA to 2-3A. Disconnected PCM: no change. Removed and disconnected cluster. Draw dropped to 8mA and stayed there. CAN plug in either connectors to cluster and can see spikes in current draw. With cluster disconnected; reconnected alternator - saw spike in current draw. Recommend replacing cluster and alternator."

Apart from this not making complete sense I was expecting a more professional approach to fault finding than merely unplugging things, so don't have any confidence in the diagnosis. As an aircraft avionics engineer I am technically literate but lack the documentation to do a more professional diagnosis. Can anyone help?

 

instead of pulling the fuses for the cluster i measure voltage drop across the fuse pins. if you see 0.1v or more across the fuse, its drawing power.
go to the pdc and check these fuses that feed the cluster

14
17
29
25amp pdc circuit breaker is the final power supply to the cluster.

for the ones that have voltage, pull them them measure parasitic draw of the system. it should not be more than 50mA after all the modules enter sleep mode.

 

Hi Primem,

I tried measuring voltage drop across each of the fuses you suggested. I got 0V across them all and just to be sure also pulled each fuse to measure the current, which was 0A. I suspect that it is not the Cluster that is drawing the current but an item that the cluster is turning on.

Do you or anybody else know where I can buy the electrical schematics so that I can do proper fault finding?

 

Update and apologies to Primem - I stupidly didn't set my DVM to the mV scale and got some useful results.

I checked each of the rear and front fuses for parasitic draw by measuring the voltage drop as suggested by Primem with the cargo light removed. The only fuses with a voltage drop were in the rear fuse box with the following results:

Fuse 8 — 15 Amp Diagnostic Link Connector (DLC)/Wireless Control Module (WCM)/Wireless Ignition Node (WIN) - Fluctuating voltage drop between 0 and 0.3mV.
Fuse 14 — 10 Amp AC Heater Control/Cluster/Security Module - constant 5.5mV

I then inserted the multimeter in series with the battery negative and ground with the battery earth cable removed to observe the total parasitic draw. With all the fuses in place the draw was about 2 Amps.

I then removed fuses 8 and 14. The current dropped to zero and stayed zero until I replaced fuse 14. When fuse 14 was replaced the current returned to 2 Amps but after about 30 seconds fell back to zero and stayed there.

I then replaced fuse 8 and the current draw returned to 2 Amps. Removing fuse 14 reduced the draw to a fluctuating 0.1 to 1.3A.

From the above it looks like the DLC, WCM or WIN is causing the parasitic draw but the haynes schematics I have really don't give me the information I need to determine which of these modules is causing the issue or why can anybody help?

 

 

Im curious if you found the solution to the problem cause im in the same situation

 

It ended up being my radio, it was shorting the circuit and we had to replace it. I’d recommend just taking it to a dodge dealership, we tried figuring it out for months not wanting to pay what the dealership would charge but we ran out of patience and options and just ended up taking it there and they figured it out.