Technical 2010 Ducato 2.3 Multijet 130 ABS Fault: Code U1706

[Mister Jolly]

ABS light came on the other day, along with the handbrake light, ASR light & no speedo function.

Error code U1706 suggests there may be a bad connection to the ABS ECU

Also had error code P0500 which explains the speedo not working.

I suspect there may be a breakdown in the wiring near the fusebox, as this has some nasty tight bends which may have caused a break inside the insulation.

Does anyone have a guide to pinout voltages, resistance readings, etc at the ABS ECU wiring that would help me trace the fault please?

 

[Anthony489]

Hi

This page from ECU testing about ABS pump faults may be of interest: https://www.ecutesting.com/common-faults/fiat/fiat-ducato-abs-pump-fault-abs-ebd-failure/

 

[Mister Jolly]

Hi

This page from ECU testing about ABS pump faults may be of interest: https://www.ecutesting.com/common-faults/fiat/fiat-ducato-abs-pump-fault-abs-ebd-failure/

Thanks. I had found & read that page in my initial searches. It certainly seems to show the same symptoms. Before I go down that route, I'd first like to eliminate any wiring issues by testing the outputs at the ABS pump multiplug.

 

[Anthony489]

Hi again

The only information I have on ABS is from eLearn, see extracts attached. The wheel speed sensors are passive (inductive) types, which produce a regular AC waveform of increasing frequency and amplitude as the wheel speed increases. I don't know their resistance, but would expect to measure something other than an open circuit or a dead short.

 

[Mister Jolly]

Thanks again Anthony489. That is really helpful.
I think my ABS module is a different type though, as it has a lot more terminals than the one shown in the diagram. See pics attached

 

[Mister Jolly]

Just rescanned it with a different machine. Found a few other unrelated stored codes which I cleared. A rescan after clearing these gives immediately:

Body Computer: U1706 Brake system (NFR) No node on C-CAN present
&
Bosch Diesel Injection: U1706 (NCM - NFR) No signal (no node) present

I assume this is a breakdown in the C-CAN wiring between the ABS unit and the engine ECU?

Can anyone help please with identifying which wires these could be?

 

[Mister Jolly]

Think I've resolved this with the help of Anthony's wiring diagrams. I checked the fuses for the CAN circuit to find that fuse 42 had indeed blown, so I replaced the fuse and everything is now ok.

I suspect a breakdown in one of the CAN wires had created some arcing to blow the fuse, so I doubt this is the end of it......

Will update the thread if/when the drama resumes.

 

[Anthony489]

Hi

Fuse F42 is listed as supplying ABS, ESR and ESP functions, plus indirectly the half of the brake pedal switch that goes open circuit when you brake to tell the various functions that braking is in process. The other half of this switch deals independently with the brake lights.

I attach an additional schematic that shows that F42 also supplies Module M091 (Slewing Control Unit) and Module M092 (Steering angle control unit. It's a bit hard to see, but M091 seems to be near the cab floor and M092 up behind the dash near the steering column. The wire from F42 (LN = Dark Blue/Black) has a junction within the wiring loom (diamond symbol). From this junction there is a wire each to M091 and M092 (LG = Dark Blue/Yellow), plus a wire to the ABS unit M051 (LH = Dark Blue/Grey)

Any problem with this wiring may have resulted in a short and the blowing of Fuse F42. Also worth looking around the brake light switch wiring in case there has been a short from one half to the other.

 

[Mister Jolly]

Thanks again Anthony489, more really helpful info.

 

[MrChevy]

Thanks again Anthony489, more really helpful info.

Hi
I have the same error code, did this solve the problem or did it come back?