WHY CANbus waking up continuously with SCANGUAGE
Posted: Sat May 22, 2021 12:46 pm
Hi, Hoping for some advice. I’ll start with the problem and where I’ve got to so far, then backfill some data or info.
Problem is the CANbus is constantly waking up when the Scanguage is plugged in resulting in an abnormal 3A draw across the battery.
Cliff
Ford Ranger PX2 2016.
Replaced battery when a bit over 2 years old(2 years ago) as it would settle to about 12.4V (half charged in 12.0 to 12.7 V range) and was going on Lap of Oz so wanted battery in top condition.
Have never had a problem starting the car though. Battery tests always returned “Healthy. Charge battery”
Had assumed problem might have been due to smart charging of the Rangers which I had Ford turn off. Didn’t think any more about it until last week or so in preparing for a long run from Perth to Gibb River Rd. Didn’t want to risk battery failure up there.
Checked battery was settling to 12.1V to 12.3V overnight measured with multimeter across the battery terminals.
Took it to local auto-electrician who discovered after quite a bit of unsuccesful accessory (see complete list at bottom of this post) disconnection THAT when the car was locked the normal CANbus scanning asssociated with system shutdown ie polling all the modules, would never fully cease. It would go to “sleep”, then constantly wake up again and again.
When this was happening the amperage draw across the battery was around 3A which the auto electrician said was way too high. Normally there should be only a 20mA to 50mA draw when in sleep mode he said. 3A x maybe 20 hours a day = 60Ah on a 80Ah battery - not too hard to work out why the battery would draw down to 12.1 to 2.3 V. And over 2 years could impair battery due to deep cycle draw downs.
Eventually he disconnected the Scanguage 2(at the monitor) which is plugged into the 2nd OBDI(black) port and then the constant waking up, and 3A draw, STOPPED . The system went to sleep.
Interested also:
How long should it take for the CANbus scanning to complete normally ?
What kind of amperage draw would be normal during and after the post shutdown CANbus process either side of sleep mode?
Some data:
Previously the fully charged battery after driving would drop down to 12.5V to 12.4V within half hour of stopping and locking the car.
After having disconnecteed the Scanguage
Ran car to fully charged
Parked in driveway
Popped bonnet, and locked car
3:30pm 12.68V at turn off
3:35pm 12.74V
4:10pm 12.79V (increase of 0.11V in 40 minutes presumably as CANbus finished its shutdown scanning)
During the above 3 readings unlocked car a few times which might have restarted shutdown scanning. Interesting also whether having the hood up(latch switch) is monitored when vehicle is locked ?
6:00pm 12.66V ie surface charge gone and was probably used up in shutdown scanning. 12.66 pretty close to fully charged V
Next morning
7:30am 12.30V -dropped about 0.2V when car was unlocked for a minute or two with wakeup scanning happening
7:45am back up to 12.53V and holding
Previously would have been down to 12.1 to 12.3 V
So net drop over night 12.66 - 12.53 = 0.13V which isnt much considering the battery is nearly 2 years old and has had the 3A deep cycling load for the last 2 years probably reducing performance plus normal ageing
Electrical Accessory list
ARB Accent canopy – integrated to vehicle central locking, lighting etc – installed by ARB
Redarc 25A BCDC with Aux battery – (Pre LV version) Installed by ARB
Driving lights – installed by ARB
UHF Radio – installed by ARB
HEMA navigator – patched to fuse panel. Shuts down when car turned off
Caravan rear camera system. Monitor on dashboard patched to fuse panel. Normally off and switches off when car turned off
Tyre pressure monitoring system signal booster – plugged into 12V socket at rear of console
2 x USB chargers plugged into 12V sockets on dashboard(nothing plugged into them)
Not sure if these sockets go to sleep also ?
SCANGUAGE 2 connected to OBDI rear port normally
Problem is the CANbus is constantly waking up when the Scanguage is plugged in resulting in an abnormal 3A draw across the battery.
Cliff
Ford Ranger PX2 2016.
Replaced battery when a bit over 2 years old(2 years ago) as it would settle to about 12.4V (half charged in 12.0 to 12.7 V range) and was going on Lap of Oz so wanted battery in top condition.
Have never had a problem starting the car though. Battery tests always returned “Healthy. Charge battery”
Had assumed problem might have been due to smart charging of the Rangers which I had Ford turn off. Didn’t think any more about it until last week or so in preparing for a long run from Perth to Gibb River Rd. Didn’t want to risk battery failure up there.
Checked battery was settling to 12.1V to 12.3V overnight measured with multimeter across the battery terminals.
Took it to local auto-electrician who discovered after quite a bit of unsuccesful accessory (see complete list at bottom of this post) disconnection THAT when the car was locked the normal CANbus scanning asssociated with system shutdown ie polling all the modules, would never fully cease. It would go to “sleep”, then constantly wake up again and again.
When this was happening the amperage draw across the battery was around 3A which the auto electrician said was way too high. Normally there should be only a 20mA to 50mA draw when in sleep mode he said. 3A x maybe 20 hours a day = 60Ah on a 80Ah battery - not too hard to work out why the battery would draw down to 12.1 to 2.3 V. And over 2 years could impair battery due to deep cycle draw downs.
Eventually he disconnected the Scanguage 2(at the monitor) which is plugged into the 2nd OBDI(black) port and then the constant waking up, and 3A draw, STOPPED . The system went to sleep.
Interested also:
How long should it take for the CANbus scanning to complete normally ?
What kind of amperage draw would be normal during and after the post shutdown CANbus process either side of sleep mode?
Some data:
Previously the fully charged battery after driving would drop down to 12.5V to 12.4V within half hour of stopping and locking the car.
After having disconnecteed the Scanguage
Ran car to fully charged
Parked in driveway
Popped bonnet, and locked car
3:30pm 12.68V at turn off
3:35pm 12.74V
4:10pm 12.79V (increase of 0.11V in 40 minutes presumably as CANbus finished its shutdown scanning)
During the above 3 readings unlocked car a few times which might have restarted shutdown scanning. Interesting also whether having the hood up(latch switch) is monitored when vehicle is locked ?
6:00pm 12.66V ie surface charge gone and was probably used up in shutdown scanning. 12.66 pretty close to fully charged V
Next morning
7:30am 12.30V -dropped about 0.2V when car was unlocked for a minute or two with wakeup scanning happening
7:45am back up to 12.53V and holding
Previously would have been down to 12.1 to 12.3 V
So net drop over night 12.66 - 12.53 = 0.13V which isnt much considering the battery is nearly 2 years old and has had the 3A deep cycling load for the last 2 years probably reducing performance plus normal ageing
Electrical Accessory list
ARB Accent canopy – integrated to vehicle central locking, lighting etc – installed by ARB
Redarc 25A BCDC with Aux battery – (Pre LV version) Installed by ARB
Driving lights – installed by ARB
UHF Radio – installed by ARB
HEMA navigator – patched to fuse panel. Shuts down when car turned off
Caravan rear camera system. Monitor on dashboard patched to fuse panel. Normally off and switches off when car turned off
Tyre pressure monitoring system signal booster – plugged into 12V socket at rear of console
2 x USB chargers plugged into 12V sockets on dashboard(nothing plugged into them)
Not sure if these sockets go to sleep also ?
SCANGUAGE 2 connected to OBDI rear port normally