Had an accident

[Tomo]

Hey guys

I was fiddling with the VR pots trying to clean up my crank/cam sensors and slipped with the screw driver and shorted something out. I did a couple of tests and replaced D19, then found that the db37 pin 28 trace had been burnt out. I then jumpered pin 28 to S12 to get power back.

I ran some further tests with a megastim and had made decent progress. I had normal voltage at the usual places. d9, u5, d3 etc as well as 5v at all it's normal places.

However when testing the 40 pin socket I had some odd voltages. 1, 20 and 31 all have 5v, 16 has 12v which I think is normal. But I also have;

3v at pin 12
4.9v at 15
5v at 13
.001 at 14
.16 at 28
2.4 at 26 and 27
3.3 at 25
3.2 at 24
1.2 at 23
3.1 at 21 and 22

I plugged the ms3 board in and the big chip (processor?) gets slightly warm (not hot) and get no LEDs lighting up or any connectivity at all.

Any ideas? Is this still a power supply issue or something deeper?

[Tomo]

The u3 chip on the megastim is also getting quite warm to touch (almost hot)

Could it be possible that more diodes are stuffed even though the power circuit seems fine? Going off the quote below.

You should find the same voltage as the battery voltage on the following points: S12, S12C, the center legs of Q9 and Q12, the left (non-banded) end of D3, the left leg of U5, and the left (banded) end of D9.

You should have 5 volts at the following points: S5, the two +5V holes in the proto area, the right (non-banded) end of D9, the right leg of U5, the left (banded) end of D19, and pins 1, 20, and 31 of the CPU.

One diode I tested reads 4xx/4xx both ways (installed), which seems odd? (D3 I think) board isn't in front of me right now.

[Tomo]

No LEDs working on the megastim either

[Tomo]

All sorted. I bought another ms2 kit for my other car, assembled and tested the ms2 and it all came out good. Tried the ms3 daughterboard in the new main board and it was dead, I then tried the new ms2 daughterboard in the old ms3 main board and it fired up.

So the ms3 daughterboard is dead, and the old main board is fixed. Expensive mistake! So I've bought a new ms3 daughterbaord and some plastic screwdrivers as to not make the same mistake again when tuning the VR pots!

[DaveEFI]

All sorted. I bought another ms2 kit for my other car, assembled and tested the ms2 and it all came out good. Tried the ms3 daughterboard in the new main board and it was dead, I then tried the new ms2 daughterboard in the old ms3 main board and it fired up.

So the ms3 daughterboard is dead, and the old main board is fixed. Expensive mistake! So I've bought a new ms3 daughterbaord and some plastic screwdrivers as to not make the same mistake again when tuning the VR pots!

IIRC, there are some on here who can fix the daughter board at a big saving over the new price.

There is a trimming tool made for that type of pot screw. it has a plastic tube at one end which fits over the screw, with a steel blade for the slot. Much stronger than a plastic screwdriver and very safe as regards shorts.

[Tomo]

Thanks for the info Dave. I may send the ms3 off to be fixed on a future project (I have 4 project cars to do)

The car is all up and running nicely now. The only issue I'm having is noise (from the starter I assume) - I can usually start it by cranking it then letting off the key quickly when the CAS syncs randomly, as soon as I let off the key it has full sync and will start 1 out of 3 tries with a big priming pulse

Does the starter solenoid wire itself cause noise or just the motor itself? Just curious as the solenoid wire as well as the main 12v feed from the battery to the starter both run through the firewall grommet right next to the engine wiring (including the VR sensors)

[billr]

I don't think "noise" from the starter is likely the root problem. Post the MSQ and an MSL of some starts that illustrate the problem.