=jon= Posted September 27, 2017 Share Posted September 27, 2017 Hi My megasquirt has decided to pack up It's been working fine for the past few years, however last night I jumped into it and it wouldn't start. Looking at the MS lights, all 3 are on flashing very very fast, so it looks like they are continuously on. Plugging tunerstudio in, it won't connect, but if I detect ports it says that it can detect an MS in bootloader mode. I've opened up the case, the boot jumper is disconnected, and I can't see anything amiss, shorts etc. I've tried reloading the firmware, it goes through the process and it appears to accept it OK, however once it's finished installing the firmware, you end up back at the same point with Tunerstudio either not detecting it, or saying there's no firmware loaded.. Any suggestions? Thanks Jon Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted September 27, 2017 Share Posted September 27, 2017 Isn't the bootloader mode set by pulling the voltage sensing ADC pin down to 0v? If so, I'd be measuring that pin to see if it's not getting volts (perhaps a dry joint or something). If it's being detected & uploads OK there can't be lots wrong with it, and the MS2 board just plugs in so not a tricky repair if the CPU has died. Quote Link to comment Share on other sites More sharing options...
=jon= Posted September 27, 2017 Author Share Posted September 27, 2017 I'm not so sure it's actually stuck in the bootloader now - it just appears to not start up... It won't get detected by tunerstudio / the command line firmware loaders unless you put the boot jumper on. If you do so, and follow the flashing process it accepts the firmware fine, but then doesn't work afterwards... I'm curious as to why it's suddenly died though - other than connecting up a rev counter to it a few hundred miles ago, nothing else has changed... Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted September 27, 2017 Share Posted September 27, 2017 28 minutes ago, =jon= said: other than connecting up a rev counter to it a few hundred miles ago, nothing else has changed... I think you can guess what the next thing to try is then... Quote Link to comment Share on other sites More sharing options...
=jon= Posted September 27, 2017 Author Share Posted September 27, 2017 That was the first thing tried Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted September 27, 2017 Share Posted September 27, 2017 It's not some weird baud rate thing or something is it? Setting got corrupted in the MS2 or somesuch? Never played with it so not sure what can & can't be tinkered with but as I said if it talks in bootloader mode & can be flashed then the micro can't be that dead. Quote Link to comment Share on other sites More sharing options...
=jon= Posted September 27, 2017 Author Share Posted September 27, 2017 Not as far as I can tell - Tunerstudio queries the ports for all the standard baud combinations and just won't see it... I can't figure it out either - if it was the main chip, I wouldn't expect it to fire up in bootloader mode and be flashed. It it's a short somewhere causing it to get stuck in bootloader mode, then during the flash sequence when it asks you to enable/disable the flash jumper it wouldn't work. If it was a serial port chip error then the flashing wouldn't work. Am a bit stumped... Have posted on the MS forums, hopefully someone on there can shed some light! Quote Link to comment Share on other sites More sharing options...
=jon= Posted October 1, 2017 Author Share Posted October 1, 2017 Slight update - spend ages going round in circles trying to figure out what's wrong with it - in the end I took it out of the car, soldered a 12v regulated PSU to the main power feed, and..... It powered up, would successfully accept firmware and stay working as well as could be expected to running on the bench... Put it back in the car, back to the bootloader mode. Back on the bench and it's working again... Started digging round in the wiring, popped the cover on the relay board in the engine compartment, the main input fuse was melted (20A), as was the fuel pump fuse (10A from what I can tell). There's enough of a voltage drop somewhere to cause the MS to not boot up properly I've extricated the PCB from the case, the back of the board is a bit scorched and the main fuse holder has actually got hot enough to melt solder off the leg and disconnect itself... Everything else looks intact, so I've ordered some more holders from farnell and will have to go over the rest of the wiring with a meter to try and work out both why it didn't blow the fuses but melted them - I'm guessing it's something on the fuel pump side.. Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted October 2, 2017 Share Posted October 2, 2017 Has the fuse holder got wet / dirty / corroded at all? If the fuse contacts deteriorated you might find they were heating up under load. Or if something else was corroded / dry joint / bad contact and the heat was travelling / affecting nearby things like the fuses - things with plastic housing will show signs 1st by melting. Or is it just mounted somewhere it can get too hot, by radiated heat from an exhaust or the suchlike? Quote Link to comment Share on other sites More sharing options...
=jon= Posted October 2, 2017 Author Share Posted October 2, 2017 Nope - it's all clean and dry... The relay board is in a waterproof box, mounted up on the top of the firewall behind the inlet manifolds, so shouldn't get too hot... I'll replace the fuse holders, clean it up and try it again, as you said it might just be oxidation of the contacts that's caused a high resistance joint and for it all to get a bit hot... Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted October 2, 2017 Share Posted October 2, 2017 I've seen plenty of cheap fuse holders do this.... Quote Link to comment Share on other sites More sharing options...
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