bobtail84 Posted November 2, 2010 Share Posted November 2, 2010 If I have a 68HC908 with 29v and Msq loaded then removed it from the ECU as a spare would the firmware and Msq still be good to go if I refitted at a later date as needed? The reason I ask is if you have a dead short you get 'X' volts up the earth side and the CPU doesn't like it up em. If you do it enough times or with enough volts it will corrupt the firmware. Some of the symptoms are:- No advance on the VE or spark maps No PWM valve operation No cooling fan control MegaTune will not connect to ECU (but TS does...) and a few more odd things but not normally all at once. Jeff Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted November 3, 2010 Share Posted November 3, 2010 Yes, anything you flash into it will stay there forever. I suspect quite a few things on the board would object to "X" volts up the negative side, although the board is fairly well idiot-proofed on the power supply side it's not indestructable. What exactly have you managed to short that badly in the first place? Quote Link to comment Share on other sites More sharing options...
TheRecklessEngineer Posted November 3, 2010 Share Posted November 3, 2010 I can proudly confess that I stuffed one of the pins on the CPU by not reading the wiring diagram correctly. I re-jigged the code to use a spare pin. Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted November 3, 2010 Share Posted November 3, 2010 Errors on the comms could just be a dead MAX232 and/or its associated capacitors. That could well report blank tables even if the CPU itself is fine (MAX232 sends all zeros up the serial bus). The lack of PWM/fan could just be dead transistors, you can check what the micro IO pins are doing with a multimeter - see if it's actually getting signals going in & putting the right signals out. A dead transistor may pull the pin to ground if there's not enough resistance in series, so unsoldering the transistor may be in order to test it. Quote Link to comment Share on other sites More sharing options...
bobtail84 Posted November 3, 2010 Author Share Posted November 3, 2010 I suspect quite a few things on the board would object to "X" volts up the negative side, although the board is fairly well idiot-proofed on the power supply side it's not indestructable. I have 1 customer who put 12+ up the 5v side and let the smoke out and that took1 chip and some time with the multi meter to find but he did all the wiring and I got the phone calls.... What exactly have you managed to short that badly in the first place? After over 2 years running with MegaSquirt on my daily driver come comp car the toll is starting to tell. The solenoid on the LPG tank was clicking in and out from time to time( I have the system earth switching) so I new there was a short to earth somewhere but where, it's a land rover.... The light switch got hot then gave up and all the lights went out on the way to work so it was time to look for the problem. The car would not advance on the VE or spark maps so I tried to re-load the firmware but no joy it would not connect. This turned out to be a connection (very basic and silly mistake) problem. A call to you, FF and HFH for a new chip ( well, a bag of chips...) and some time again with the multimeter found the problem. So, no prizes for the right answer but what and where was the short? 10 question limit. Jeff Quote Link to comment Share on other sites More sharing options...
Hybrid_From_Hell Posted November 3, 2010 Share Posted November 3, 2010 Ooo Ooo Oooo Me Me - Over here - - can I play Mr ??? Nige Quote Link to comment Share on other sites More sharing options...
bobtail84 Posted November 3, 2010 Author Share Posted November 3, 2010 Ooo Ooo Oooo Me Me - Over here - - can I play Mr ??? Nige Eeerrrmm let me think....... NO.... Quote Link to comment Share on other sites More sharing options...
bobtail84 Posted November 10, 2010 Author Share Posted November 10, 2010 No takers then... Quote Link to comment Share on other sites More sharing options...
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