klancf51
Silver Member
Farmall 70A no start – ADIC (Analog Digital Instrument Cluster) displayed “Stop Sign” icon and DTC 3157. Also, once, briefly displayed DTC 14901. The tractor had been sitting outside for about 10 days.
• We visually inspected the main wiring harness from the ECU back to the ADIC .
• We disconnected the wiring harness connectors from the ECU and re-connected them.
• We jump started the tractor successfully. After disconnecting the jumper cables, it ran for a few minutes and shut down with DTC 3157.
• We charged the battery. Again, it started and ran for a few minutes and shut down with DTC 3157.
• The next morning. we removed the battery, put it on the charger; meanwhile sprayed the grounding bolts in the battery compartment with brake cleaner and tightened them. Battery ground cable was not fully secure to frame and tightened ~ 1/8 turn. Re-installed the charged battery. Afterwards, tractor started and ran normally.
The reason we were suspicious of the battery and grounding is that for most ECU-related issues, the Farmall 70A Service Manual suggests “faulty supply voltage or ground, missing” as the #1 failure mode. The reason is that not all units on the CAN bus switch off communication at the same voltage level. This creates the situation where some components or control units are trying to communicate with switched-off units. Key takeaway: Always verify a properly charged battery and charging system as the first step in troubleshooting a CAN bus comms issue.
Btw, the DTC codes listed in the Farmall 70A Service Manual do not numerically correspond with those displayed on the ADIC. The Service Manual uses hexadecimal codes AND they don't convert directly to the DTCs on the ADIC. CASE IH should address this.
Update:
About 2 weeks later, DTC 3157 returned intermittently. Shortly after, the tractor would not crank intermittently and show a low battery voltage (~11.6 V) on the ADIC. When it would crank, the engine would start, but die seconds later. Sometimes it would start and run normally. Eventually, I was able to diagnose a fault in the ignition switch and replaced it. At the same time I replaced the ECU relay K-001 and the Cranking relay K-002. The ignition switch had failed - there is no doubt about that.
The unit is now starting & running "tip-top"; I would even say "like new". Displaying normal voltage (~12.6 V) consistently.
Note:
DTC 3157 - ECU Not Detected on CAN bus.
DTC 14901 – ECU not present
DTC 14901 – ECU not present
• We visually inspected the main wiring harness from the ECU back to the ADIC .
• We disconnected the wiring harness connectors from the ECU and re-connected them.
• We jump started the tractor successfully. After disconnecting the jumper cables, it ran for a few minutes and shut down with DTC 3157.
• We charged the battery. Again, it started and ran for a few minutes and shut down with DTC 3157.
• The next morning. we removed the battery, put it on the charger; meanwhile sprayed the grounding bolts in the battery compartment with brake cleaner and tightened them. Battery ground cable was not fully secure to frame and tightened ~ 1/8 turn. Re-installed the charged battery. Afterwards, tractor started and ran normally.
The reason we were suspicious of the battery and grounding is that for most ECU-related issues, the Farmall 70A Service Manual suggests “faulty supply voltage or ground, missing” as the #1 failure mode. The reason is that not all units on the CAN bus switch off communication at the same voltage level. This creates the situation where some components or control units are trying to communicate with switched-off units. Key takeaway: Always verify a properly charged battery and charging system as the first step in troubleshooting a CAN bus comms issue.
Btw, the DTC codes listed in the Farmall 70A Service Manual do not numerically correspond with those displayed on the ADIC. The Service Manual uses hexadecimal codes AND they don't convert directly to the DTCs on the ADIC. CASE IH should address this.
Update:
About 2 weeks later, DTC 3157 returned intermittently. Shortly after, the tractor would not crank intermittently and show a low battery voltage (~11.6 V) on the ADIC. When it would crank, the engine would start, but die seconds later. Sometimes it would start and run normally. Eventually, I was able to diagnose a fault in the ignition switch and replaced it. At the same time I replaced the ECU relay K-001 and the Cranking relay K-002. The ignition switch had failed - there is no doubt about that.
The unit is now starting & running "tip-top"; I would even say "like new". Displaying normal voltage (~12.6 V) consistently.
Note:
- The original ignition (#84280152) has been discontinued and the current part is #90414993.
- I replaced the OE Omron relays with sealed units.
- To replace the ignition switch, it isn't necessary to pull the steering wheel. However, it is necessary to remove the shuttle lever and hand throttle knob in order to lift the dash cowl enough to access the ignition switch.
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