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

I just unpacked my MSII, relay board and wiring harness. Looking at the drawing included in the wiring harness it matches the manual and I understand it. When looking at the relay board with the same DB37 connector and screw block clearly labelled for all injectors and sensors and now I am confused. Does the wiring harness connect directly to the relay board and then out the engine/sensors? If so then I need to build a small wiring harness from the DB37 on MSII to the screw block on the relay board. Is this correct? The extra DB9 confused me as well - tuning cable?

I am going to keep them both inside the passenger compartment so they will be close together and near the battery.

Sorry for what may end up being a silly question!

Thanks

The DB9 is a tuning cable connection - if this is a V3.57, there is also a DB15, but a standard build will not use it (it's for optional I/O features).

You would use a DB37 to DB37 cable to connect the MS to the relay board. This needs to be one that can handle a decent amount of current; a computer cable will not work here.

If I use the DB37 to DB37 to connect to the relay board then do I use the screw posts on the relay board to go to my sensors? If so then I do not need the pre-assembled wiring harness correct? This seems really odd - the wiring harness is going to save me a lot of time and effort. The relay board is not getting me vey much for the cost and the additional labor for fuse protection and relays.

They appear to mutually exclusive - MSII and the wiring harness then build your own relay/fuse portion OR MSII to relay board with a custom DB37 wiring harness then a custom wiring harness to the sensors.

Am I correct?

pcf_mark wrote:If I use the DB37 to DB37 to connect to the relay board then do I use the screw posts on the relay board to go to my sensors? If so then I do not need the pre-assembled wiring harness correct? This seems really odd - the wiring harness is going to save me a lot of time and effort. The relay board is not getting me vey much for the cost and the additional labor for fuse protection and relays.


They appear to mutually exclusive - MSII and the wiring harness then build your own relay/fuse portion OR MSII to relay board with a custom DB37 wiring harness then a custom wiring harness to the sensors.

Am I correct?

The DB37 is the pre-assembled wiring harness

You need the pre-assembled wire harness to connect MegaSquirt to the relay board.

This is the pre-assembled harness to connect the MegaSquirt to the relay board.
http://www.DIYAutoTune.com/catalog/mega ... -p-47.html

"I use the screw posts on the relay board to go to my sensors?"

Yes, using the screw posts on the relay board. You fabricate a custom harness to connect the relay board to the engine sensors.
The cheapest way, to fabricate the relay board to engine harness is to get a wire harness from a local Pick a Part. Get a harness from a fuel injected version of the engine you are going to MegaSquirt.
By the way, what engine are you working on.

Now that I have read your posts and looked at everything again I think I understand a little more. I purchased this wiring harness http://www.DIYAutoTune.com/catalog/1239 ... -p-43.html which connects the MSII directly to the sensors.

What I need to make use of the relay board is to connect the relay board and MS together with a DB37 to DB37 cable like the example Ollie shared http://www.DIYAutoTune.com/catalog/mega ... -p-47.html. To make this with the parts I have can I cut off a the DB37 with a pigtail and then solder another DB37 on the end? Using this I could join the MS and relay board and still have the correct wire colors and shielding (?). Then use the balance of the wire left over that is nicley labeled to go from the screw posts on the relay board to the sensors. Correct?

Before I start cutting I was hoping to get a sanity check!

Thanks
Mark

To avoid any issues I am getting the correct relay to MS cable and wiring bundle. Thanks!