Isolation error on external negative side
•Turn off and lock the interlock loop control switch S229. Read Insulation Error Status with SDP3. Perform visual inspection of VCB cables, if damaged cable found, replace cable. NOTE! Replacing of cables and fault tracing from here on is considered an electrical work and shall only be performed by Scania certified personnel. Vehicle shall be made safe according to electrical work procedure. •If no visual damage is found remove the flange with cable fittings that connects to the MGU from the VCB central electric unit P7 according to instruction in multi. Perform manual resistance measurement between positive and negative terminal in the VCB central electrical unit(P7). Repeat measurement between positive and negative VCB ring connectors on the flange to the MGU to distinguish whether the fault is present on the MGS side or in the HRU/HPU. •To further trace fault disconnect all VCB cables and perform manual measurement on each respective cable, then on each respective component until fault is traced. Replace faulty component according to spare part plan. •If all cables and other components can be excluded replace the IBU according to instruction in multi. NOTE! Replacing the IBU is considered an electrical work and shall only be performed by Scania certified personnel. Vehicle shall be made safe according to electrical work procedure.
What you'll see
No driver-visible symptom recorded.
System reaction
Single insulation fault Value: Reaction: <400kΩ Amber warning in ICL <100kΩ RES safe shut down within 1s Double insulation fault Value: Reaction: <400kΩ Amber warning in ICL <100kΩ RES safe shut down within 1s <1Ω RES fuse blown
Diagnostic depth
Detected by IBU insulation fault diagnostics and reported to BMU. Appropriate DTC set by BMU. Detection possible through manual measurement or through SDP3 read out.
• Chafing on VCB cables • Short circuit of pole to ground capacitors • Internal faults in VCB components.