Fuel pump circuit

[ur2slo]

Ive never gotten my fuel circuit to work. Im not sure if I fried something or didnt assemble something right. The car runs fine otherwise.
Shouldnt megasquirt be putting out a ground signal on the fuel pump wire? Im not getting it, Maybe 5 volts positive
What did I do wrong?
ITs a 93 Plymouth Duster 3L turbo
Thanks

[Matt Cramer]

Yes, it should put out a ground signal. Does it work OK on a Stim?

[ur2slo]

First time I plugged the stim in since I built it. Now I'm not getting rpm readings out of it. Works in the car. The PMP led is lit up.

[Matt Cramer]

Does the PMP LED stay on (if it is, something's shorted) or turn off after 2 seconds of not seeing RPM (which it should)?

[ur2slo]

No it stayed on, unfortunately.
Is it fixable?
Thanks for your help

[Matt Cramer]

It can probably be fixed. What main board do you have?

[ur2slo]

MS2 V3.0

[Matt Cramer]

Ok, here's the relevant schematic:



First, put it on the Stim and check if there's 5 volts coming into R16 (that's the turn on signal).

[ur2slo]

I'll check that when I get home tonight. Can you tell me the next step to check if I do or don't have the 5v at R16?

[SymTech Laboratories]

I'll check that when I get home tonight. Can you tell me the next step to check if I do or don't have the 5v at R16?

We would reload the firmware next. If that doesn't change anything, you may need a new processor.

[ur2slo]

I'm getting 2.4v

[SymTech Laboratories]

I'm getting 2.4v

On both sides of R19? Is Q19 shorted anywhere? Is Q19 inserted the right way? Is R40 the correct value (1 ohm)?

[ur2slo]

Ok. With fresh batteries in the stim and meter I'm getting 1.822v going in and 64.1mv coming out of R16.
R40 is 1.4 ohm

[SymTech Laboratories]

R40 is 1.4 ohm

You might try replacing R40 with a 1 ohm resistor. With a 1.4 ohm resistor, the current will be limited to just ~500mA.

[ur2slo]

It's the right resistor in there, could I be getting that reading because it's in the board?

[ur2slo]

Can I get a link to the proper firmware?
Thanks

[jsmcortina]

Under the Downloads section in the manual. http://www.msextra.com/doc/index.html#ms2

James

[ur2slo]

Downloaded new firmware, same problem
PMP stays on and no rpms from stim

[ur2slo]

Any ideas, I'd like this setup to work like it was meant to

[SymTech Laboratories]

It's the right resistor in there, could I be getting that reading because it's in the board?

You can measure voltage in-system, but not resistance.

You might try posting a few clear pictures of the top and underside of your MegaSquirt board for us to spot any obvious problems.