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

Hello,
I am installing a MSII v3.57 onto a 4 cylinder chevy cavalier. I read in the manual how to wire it up and I am a little confused. The manual says to set the megasquirt up just like for HEI system and it also uses the bypass relay the same way. I understand that part. The part I am having trouble with is the DIS module.

I am not sure what DIS module the manual is referring to because the pin description doesn't match the HEI section 7 pin, which I was referenced to while reading.

Could someone please explain which DIS module the manual is referring to for the GM DIS? My ICM on my car doesn't match any of these. Will a 7 PIN work for a 4 cylinder, 2 coil wasted spark DIS system.

Thank you

You would use a module something like this:



Note that this is the six cylinder version; yours may be a bit different depending on exactly what Cavalier engine you have. If it is an OBD-II unit, you'll need to get the module off an OBD-I car. What year and engine type is this?

The engine is a 1999 OBDII chevy cavalier 2.4L LD9. So I could use one of a earlier OBD1 chevy cavalier 4 cylinder correct?

Thanks a ton for the help!

Yes, you'll need one from an OBD-I Cavalier or Saturn. A '99 would be missing the module as it is integrated into the ECU.

We (saturn guys) have found that you need to modify the EST wire (adv signal) between the MS and the ignition module. At high rpms and heavy ignition loads (10+ psi of boost) the ignition module acts up due to too much voltage supplied from the MS. The saturn ICM uses a 0-5v signal, the MS sends out 0-12 signal.

All you need to do is install a 10K ohm resistor on the adv signal wire and the problem goes away.

Thanks a ton for your help guys! I just picked up a 1993 saturn OBD1 ICM, and coils at the junk yard for 25 bucks. I hope it works.

S. Bretz, I have a questions for you since you are a saturn guy.

I have been studdying the MegaSquirt Manual GM DIS section and the wire colors and the pin locations and it says
• Module pin B or C - white wire - DB37 #36 (V3 main board, ignition output signal pin for V2.2),
• Module pin A - tan/black wire - Connect to a bypass relay as shown for the HEI modules,
• Module pin E - purple/white wire - DB37 pin #24 (tach),
• Module pin F - red/black wire - ground,
• Module separate connector - black/white - ground,
• The module also has connections for power (pink), the crank position sensor (yellow & purple), and tach (white).
Note: it appears some modules use other connections (but use the same wire colors for the same functions). For example, some of the the 2.8 and 3.1 V6 engines have the Tach (white) on C, and the Bypass (tan/black) on A. Most of the remaining wiring (power and VR sensor) appears to be constant.

So My question is that the saturn ICM I have has the same colors in different pin locations. So Just use the wire color and disregard the pin letter?

There are to connectors on the ICM. one has letters A-E and the other has letters A-F.
A-E connector A-F Connector
A-Yellow, VR signal A-Pink Black, 12 volts input?
B-Purple, VR signal B-Yellow Black, ???
C-no wire C-White,DB37 pin #36 V3 main board, Is This the EST wire?
D-Black Red, Ground D-Purple White, DB37 pin #24 (tach)
E-Black White, Ground? E-White, ???
F-Tan Black, Bypass Relay

Is this right?

Thanks again

The above message to my question got merged together. Any one have any Ideas corrections to what I have here? It is a 1993, 4 cylinder saturn ICM and the below is how the 2 connectors are from the factory.

I have already had to repair my MSII once form a mistake, really trying to avoid that again

A-E connector
A-Yellow, VR signal
B-Purple, VR signal
C-no wire
D-Black Red, Ground
E-Black White, Ground?

A-F Connector
A-Pink Black, 12 volts input?
B-Yellow Black, ???
C-White,DB37 pin #36 V3 main board, Is This the EST wire?
D-Purple White, DB37 pin #24 (tach)
E-White, ???
F-Tan Black, Bypass Relay

Thanks

The colors are correct, saturn just uses different pin locations.

Does the the ICM from the Saturn need to be mounted to a grounded surface? I have a great spot to mount it but the surface is plastic. I wouldn't think it needs to be because there are already two ground wires in the harness. I just thought I would ask before mount it and button everything up.

Thanks

S. Bretz

Would you mind filling me in on what your ignition settings are for your saturn ICM. I am having trouble getting RPM to display in megatune while I am cranking. I tried to data log while cranking too but think I messed up somewhere on that.

Thank you!