MSefi.com read only forum (Jan.15,2018)

I got the Car to run!! It fired up with no problem after 8 months of bench/stim testing and hardware install on the engine, and it ran all day while I tune. I was the happiest dude in these United States of America.

As you know this requires a lot of switching on and off of the system while tuning.
Well needless to say now the ECU does not power up at all, the last time I switched it on, the fuel pump engaged and immediately disengaged (two separate occasions back to back) then that was it.

I looked at all the schematics avail on the site and tried some of the troubleshooting:

I’ve taken it apart and ran some tests on the main board according to line 23 in the the assembly and troubleshooting guide. With the CPU removed.
“ there should be 5 volts between pins 19 (ground) and 20 (+5), there should also be +5 on pin 1 and 31 (check against ground at pin 19), and ground potential on pins 2 and 32 (check against +5V on pin 20)…


I get 4.99V on pins 19 and 20
I get 4.98V on pins 1 ans 31 when checked against pin#19
I get 4.99V on pin# 20 with pin #2 as ground... But
I get 0.00V on pin# 32 when checked against pin #20

I am checking the schematics on the sites but not making much headway.

P.S the U5 voltage regulator checks out just fine.

Any further assistance would really, really help .
Thanks

I get 0.00V on pin# 32 when checked against pin #20

Was that a typo? Pins 32 and 20 are both grounds.

If the fuel pump runs and then stops at switch on, it means the processor is at least doing something. With it completely dead, this wouldn't happen. What happens if you connect Tuner Studio? Or get it to look for an MS?

Matt Cramer wrote:

I get 0.00V on pin# 32 when checked against pin #20

Was that a typo? Pins 32 and 20 are both grounds.

Yes that was a mis-read; I meant 31 and 32. At one point I wasn't getting any reading; I removed one leg of most of my diodes and is now getting appropriate voltages at all points on the U1 (40 pin socket)

trakkies wrote:If the fuel pump runs and then stops at switch on, it means the processor is at least doing something. With it completely dead, this wouldn't happen. What happens if you connect Tuner Studio? Or get it to look for an MS?

The car ran for two days: I am aware that the pump would prime the system for about 1.5 to 2 sec before start up.

but this was a different situation, When I switched on the the car the pump turned on as it should but not for 1.5 to 2 sec this time, much shorter stopped; then engaged again without me touching the keys; after that the ECU never powered up again, Dead...

It was been 4-5 days now, So I am definitely in the dark here.

Matt did communicate with me to test for voltage points in various places..

"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."

My results are: With board minus CPU connected to car;
Searching for 12V as per your instructions
S12-11.92V
S12c-11.22V
Q9-11.92V
Q12-11.92V
D3-11.92V
U5-11.24V

For the 5V search results
S5-4.97V
Proto-4.97 on both holes
D9-4.98V
U5-4.98V
D19-4.97V
Pins 1, 20, 31-4.97V

The ECU seems to be powering on OK. What happens if you try loading firmware?