2010 Ducato 250 2.3L Diesel Turbo
I've got a parasitic draw that will drain the battery enough over a few days of not driving to make the engine hard to start. Measuring at the negative battery cable with my Uni-T UT201E Clamp Meter it usually show around 190ma of draw with the reading bouncing around 20 - 30ma. If I pull the F39 fuse the draw drops by about 70ma and becomes stable - it stops jumping around. Also, the blue led light to the left of the steering wheel which indicates the security system is active goes out. Now I'm not sure how accurate my clamp meter is at such low current, but it's clear that pulling that fuse drops the draw. No other fuse I pulled under the dash had any affect.
There are two codes which won't go away, U1602 CAN Line, Bus Off Intermittent in the Marelli Instrument Cluster, and D602 CAN Line Error, Bus Off in the Body Computer. These two codes come back immediately after clearing DTCs. I've also seen various other DTCs from other modules relating to failures to communicate with the Instrument Panel / Cluster, but those are rare and don't come back after being cleared.
So I had a theory that my parasitic draw might be due to a communication error on the CAN bus not allowing all modules to go to sleep. So I hooked up my PicoScope and took a quick look via the B CAN pins, 6 and 14, on the OBDII connector. My first observation was that the voltages weren't what I expected. I've read that B CAN high and low should switch between 2.5 - 3.5v and 2.5 to 1.5 volts respectively. I saw signals switching from 5v to 1v and 0v to 4v. However the signals looked well formed and the two were always the inverse of each other so I'm guessing maybe that's just a non-standard Fiat thing? Anyways, when I switch the engine off, the signals at the OBDII connector continue until I engage the alarm system and then they stop. As a note there is a third party immobilizer system installed.
So that seems like a dead end unless the gateway in the NBC disconnects the bus from the OBDII connector when the alarm is activated.
Getting back to the F39 fuse. On page 120 of the Training Manual it lists everything on F39:
On page 180 and 181 of the training manual it discusses the CSA and CAV.
Specifically, on 180 it says:
As a note, on page 181 it shows there is a button to disable the tilt sensor, and that button isn't present on my vehicle.
So is it reasonable at this point to assume that my vehicle only has the third party security system, and that that is the cause of my parasitic draw? I want to be sure, since the company that installed the system will charge me through the nose if I send it in for diagnosis and it turns out not to be their system.
Is there anything I'm missing?
I've got a parasitic draw that will drain the battery enough over a few days of not driving to make the engine hard to start. Measuring at the negative battery cable with my Uni-T UT201E Clamp Meter it usually show around 190ma of draw with the reading bouncing around 20 - 30ma. If I pull the F39 fuse the draw drops by about 70ma and becomes stable - it stops jumping around. Also, the blue led light to the left of the steering wheel which indicates the security system is active goes out. Now I'm not sure how accurate my clamp meter is at such low current, but it's clear that pulling that fuse drops the draw. No other fuse I pulled under the dash had any affect.
There are two codes which won't go away, U1602 CAN Line, Bus Off Intermittent in the Marelli Instrument Cluster, and D602 CAN Line Error, Bus Off in the Body Computer. These two codes come back immediately after clearing DTCs. I've also seen various other DTCs from other modules relating to failures to communicate with the Instrument Panel / Cluster, but those are rare and don't come back after being cleared.
So I had a theory that my parasitic draw might be due to a communication error on the CAN bus not allowing all modules to go to sleep. So I hooked up my PicoScope and took a quick look via the B CAN pins, 6 and 14, on the OBDII connector. My first observation was that the voltages weren't what I expected. I've read that B CAN high and low should switch between 2.5 - 3.5v and 2.5 to 1.5 volts respectively. I saw signals switching from 5v to 1v and 0v to 4v. However the signals looked well formed and the two were always the inverse of each other so I'm guessing maybe that's just a non-standard Fiat thing? Anyways, when I switch the engine off, the signals at the OBDII connector continue until I engage the alarm system and then they stop. As a note there is a third party immobilizer system installed.
So that seems like a dead end unless the gateway in the NBC disconnects the bus from the OBDII connector when the alarm is activated.
Getting back to the F39 fuse. On page 120 of the Training Manual it lists everything on F39:
- NRR, diagnosis socket EOBD, CSA, CAV, CCT, A/C control, Webasto timer
On page 180 and 181 of the training manual it discusses the CSA and CAV.
Specifically, on 180 it says:
Does this mean the the built in alarm system, the CSA annd CAV are optional and might be completely supplanted by the third party immobilizer system?
As a note, on page 181 it shows there is a button to disable the tilt sensor, and that button isn't present on my vehicle.
So is it reasonable at this point to assume that my vehicle only has the third party security system, and that that is the cause of my parasitic draw? I want to be sure, since the company that installed the system will charge me through the nose if I send it in for diagnosis and it turns out not to be their system.
Is there anything I'm missing?
