Can Bus Problem

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dfidalgo
Posts: 12
Joined: 21 Feb 2024, 12:24
x 1

Can Bus Problem

Post by dfidalgo »

Hi guys,

I'm desperate with my Boxer 2.2 hdi, she does not start with a fault in communication with the Injection ECU. The immobilizer stays On, she cranks but no start.

I checked the C Can lines L & H, and the resistance between both is 120ohm.

Can L & H are showing no resistance to battery 12v, and if I measure the Can line to battery positive is showing the battery voltage.

When I disconnect the ABS plug, that short circuit seems to disappear.

I tried to bypass the ABS module (connecting CAN wires directly without the ABS in the middle), but the short seems to get back.

I tried to reconnect the ABS module and bypass the injection ECU (to despite a ecu fault) and the short comes again.

I don't know if that measurements makes any sense, or I'm just making a no sense measurement.

The van is stopped in the street, passed 3 days now and I'm really desperate.

I don't have oscilloscope and I don't know what more I can do/check,.

Anybody can help here?

Thanks in advance,

Daniel
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wheeler
Posts: 6931
Joined: 21 Sep 2002, 19:07
x 747

Re: Can Bus Problem

Post by wheeler »

Any recent work done before this happened or any accessories/modifications made?
What were the circumstances? did the engine stop whilst driving or would it just not restart after stopping?

Have you measured each of the CAN pairs at the ABS plug with is disconnected? You effectively need to look 'each way' to see if the fault is on the Injection ECU side or the BSI side.
Do the resistance check, each pair should read 120 ohms then check for shorted together, to earth & to positive.
dfidalgo
Posts: 12
Joined: 21 Feb 2024, 12:24
x 1

Re: Can Bus Problem

Post by dfidalgo »

Hi wheeler, thank you for your response.
wheeler wrote: 29 Feb 2024, 11:05 Any recent work done before this happened or any accessories/modifications made?
No accessories or modifications were made, but coincidentally I was measuring the G1 (or G2) pin from the ECU brown connector. The problem started after this.
wheeler wrote: 29 Feb 2024, 11:05
Have you measured each of the CAN pairs at the ABS plug with is disconnected? You effectively need to look 'each way' to see if the fault is on the Injection ECU side or the BSI side.
Do the resistance check, each pair should read 120 ohms then check for shorted together, to earth & to positive.
Resistance between CAN L & CAN H measured on BSI (disconnected from ABS & ECU, battery disconnected too) is 118.9 OHM.

Resistance between CAN L & CAN H measured on ECU (disconnected from ABS & BSI, battery disconnected too) is 120 OHM.

Checked for shorted together, to earth & to positive and the only suspicious results was the short to ground test:
CAN L to ground: 22ohm
CAN H to ground: 139ohm


When all pairs are connected, I get 120 OHM too (never saw 60 OHM on the CAN bus).

The odd thing is that I measured today the voltage on CAN L (to ground) & CAN H (to ground) on ECU, ABS and in BSI, the BSI show no voltage on CAN lines.

It seems that the CAN bus is dead? Problem starts on BSI?


Best regards,

Daniel
dfidalgo
Posts: 12
Joined: 21 Feb 2024, 12:24
x 1

Re: Can Bus Problem

Post by dfidalgo »

SOLVED

The Can Bus A82C250 controller in BSI was defective. After changed this microcontroller the BSI came back to life again, but the CAN data was intermittent.
When I touched the BSI connector (CAN wires) I realized that it had a bad contact too in this connector.
I opened up the BSI again, and resoldered the connector pins.
All CAN problems are solved now.

Best regards,
Daniel
wheeler
Posts: 6931
Joined: 21 Sep 2002, 19:07
x 747

Re: Can Bus Problem

Post by wheeler »

Nice work, do you have a picture & location of this A82C250 controller (whatever that is😂) inside the BSI?
dfidalgo
Posts: 12
Joined: 21 Feb 2024, 12:24
x 1

Re: Can Bus Problem

Post by dfidalgo »

Sure, here it go 🙂
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