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Hey Folks There are not a lot of good sources out there for troubleshooting and diagnosing ECU problems with the Massimo Buck, Bennche Bighorn, Bennche Cowboy, & Cazador machines that use the Delphi MT05 ECU. They are all basically the same with different badging, so I thought I'd share some info that I found during some searches. I was trying to help someone diagnose and repair a hard starting issue. The ignition coil was throwing a 0351 code. I discovered how to read codes without an OBDII code reader. The following procedures should help you check your fault codes and clear them if needed. Fault Code Troubleshooting for Delphi MT05 ECU on the Massimo Buck 400, Bennche Bighorn 400, Bennche Cowboy 400, and Cazador 400 *NOTE: The MT05 ECU is not really OBD 2 compliant. It is much more similar to an OBDI system. The MT05 ECU controls either 1 or 2 cylinder engines commonly found on Massimo, Bennche, and Cazador. Much of the ECU info was found here: https://netcult.ch/elmue/HUD ECU Hacker/Delphi MT05 Manual.pdf Delphi EFI System Design Delphi EFI employs 5 sensors to monitor engine performance. 1. Crankshaft Position Sensor 2. Coolant Temperature Sensor 3. Oxygen Sensor 4. Throttle Position Sensor 5. Manifold Air Pressure/Manifold Air Temperature (MAP/MAT) Sensor Delphi EFI employs the following system components. 1. MT05 Engine Control Unit (ECU) 2. Fuel Pump 3. Multec 3.5 Fuel Injector 4. Idle Speed Control Valve (Idle Stepper Motor) 5. Multec Ignition Coil 6. Fuel Vapor Canister Purge Valve Using the Digital Dashboard to Decipher EFI Trouble Codes In addition to commercially available diagnostic scan tools (Big $$$), you can use the engine warning light of the Siemens dashboard to diagnose most of your EFI problems. The digital dashboard receives signals from the MT05 ECU, and the engine warning light will flash a diagnostic trouble code (DTC) if the ignition key is switched on/off for three cycles. When you turn on the ignition, the engine warning light will illuminate, which indicates the EFI system is operational. After the engine is started, the engine warning light will extinguish if the EFI system is working properly. However, if the engine warning light remains illuminated, it indicates the EFI system is not working properly, and there is a system component failure. Deciphering Diagnostic Trouble Codes To read the diagnostic trouble code (DTC), open and close the ignition key three times in rapid succession, as follows: open/close—open/close—open. At this point the engine warning light will flash a DTC which indicates the fault in the EFI system. Refer to the attached fault code table to identify the corresponding problem. The engine warning light will emit a sequence of flashing lights. If the light flashes 10 times, the translated number is 0. If the light flashes one time, the translated number is 1, et cetera. For example, if the MAP/MAT sensor is disconnected, or the connector is shorted to ground, the engine warning light will flash in the following manner (This is an example only). The engine warning light will flash 10 times: The first number of the DTC is 0 After an interval of 1.2 seconds, the engine warning light will flash 1 time: The second number of the DTC is 1 After an interval of 1.2 seconds, the engine warning light will flash 10 times: The third number of the DTC is 0 After an interval of 1.2 seconds, the engine warning light will flash 7 times: The fourth number of the DTC is 7 The resulting DTC is P0107. NOTE: For the system I was helping to troubleshoot, I suspected an ignition coil failure due to the code that was thrown. When it was checked, it was flashing: 10, 3, 5, 1. The 10 represents a 0. So the actual code was 0351. After finding the code, the coil wire was checked and discovered loose at the spark plug. Once it was pushed fully on, the problem was fixed. Most likely, this problem was created after the owner had pulled the spark plug to check the gap. The ECU was rebooted using the procedures detailed below with no more codes being thrown. If there are other fault codes, the engine warning light will flash the next code in 3.2 seconds after finishing the first sequence. After all existing fault codes are flashed, the engine warning light will repeat the fault codes in a loop sequence, until the ignition key is turned off. To clear fault codes you either need an OBDII Fault Code reader and a Delphi 6 pin connector adapter cable that you have to order from China and wait 8 weeks…OR....you can simply reboot the ECU using the instructions detailed below. Rebooting the ECU Perform the following steps to reboot the ECU. 1. Turn off the ignition for 15 seconds. 2. Turn the ignition on/off for 5 cycles. Make sure each cycle lasts about ½ second, verifying the start of the fuel pump for each cycle. If the fuel pump doesn't start during any cycle, begin the entire reboot procedure from the beginning. 3. Turn off the ignition for 15 seconds. TPS (throttle position sensor) re-learn procedure after rebooting ECU. This should be done after replacing the TPS or the ECU....and it is advisable to check proper idle after rebooting an ECU too. Source: ECU Hacker (Reworded process slightly to make it a more sensible flow in my mind): 1. Turn the idle screw one full turn clockwise before starting 2. Start the engine, and run at low idle until the engine warms. Maybe a couple of mins. 3. Idle should be above 1500 rpm. If it isn’t, turn it up to 1700 then shut the engine off. Do another reboot of ECU. 4. Restart the engine and let it stabilize at 1700 rpm. Then turn the idle screen down to 1500 rpm and let it stabilize for a few seconds. Once it stabilizes, set to the final recommended idle speed for your machine. The placard under (or behind) your seat should show idle speed, valve adjustment, spark gap, etc. Typically the 390 cc engines in the "400" machines run at 1600 rpm idle. 5. Shut it down. Wait 10-15 seconds before restarting. The procedure is now complete. Final Notes: I have included pictures of an OBDII connector and the Delphi 6 pin connector in case anyone wants to go buy stuff off ebay or local parts suppliers and build a connector to use for an OBDII reader. But...you can save money and simply do the same thing with code reading and resetting using the check engine light on your dash. Some folks prefer to do it with code readers. Hope the information provided helps if anyone ever needs it but cannot find it in repair manuals. I discovered most of this in some motorcycle forums. The source for the diagrams is here: https://netcult.ch/elmue/HUD ECU Hacker/ Be advised: I am not a service technician. I do not endorse any manufacturers. I do not get paid to help, nor do I want to. This is just a hobby of mine. I enjoy working on things and solving problems. If you run into a weird problem that stumps you, give me a shout. I may be able to give you some ideas...or not. Just know, that troubleshooting thru emails can be challenging. The more info you can provide, the better. Otherwise, I will probably ask you a ton of questions. The good news is, the Delphi system used on these machines is essentially an OBDI and it is very simplistic. If you are methodical and patient, most of your "problems" can be figured out thru a process of elimination. Always go for the simple things first before throwing money and sensors at a machine. Take care - JT

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