I am switching my car to a MS II system while the car is down. I am looking on what I need to tap into the C207 for the fuel pump turn-on etc(1987 Iroc 5-speed if it matters).

I am using the existing wiring harness so the connecters are already in the harness....


I have a link to the diagrams on the Austin Thirdgen site, BUT please dumb it down for me

 

Up!

 

I'm working off of memory here, so pardon any mistakes on my part. The factory ECM fuel pump signal is reverse polarity from the MS2. I believe the factory ECM sends a +12v signal to the relay, which is hooked to ground on the other terminal. Meanwhile the MS2 pin 37 fuel pump output sends a GROUND signal for the fuel pump relay. This means you'll have to do one of two things:

1> Rewire at the fuel pump relay to supply a +12v IGN power to the relay where the terminal where Dark Green/White ECM signal wire normally goes. Then cut the ground wire and hook the dark grn/wht ECM signal wire directly to that side of the relay. Now wire pin 37 "fuel pump output" from the MS2 to the dark grn/white wire.

2> Leave all wiring as is and use a relay on the output of Pin 37 of the MS2. Wire it to trigger the relay, which has one side of the pole wired to ground. Connect the other pole to the dark grn/white wire that runs to the fuel pump relay.

I prefer less relays and since I made my own harness, so I just did the rewire at the factor fuel pump relay itself.

Now it has been a while since I did this so make sure you verifiy all of this with the diagrams before you power this thing up! Hope this helps.

Steve

 

OK, I get the basis that I need to reverse the signal from the MS to the signal to the green/white wire as it is normaly receiving +12, but the MS fuel pump output sends a ground....

ANy other wires on that harness need to be used in this setup from the c207?

 

Anything else I need to worry about in ths connector?

 

The MS unit I played with 4+ years ago had that 9 pin D connector on it, and I had a hell of a time getting it to work with any laptop available.....

did they ever upgrade it to a USB port??

 

Yes, the version 3.57 SMD MS board has a USB connection and a Compact Flash or other SSD card socket...

As for the OP, the fuel pump is GROUNDED by the ECM (almost ALL of the ECM outputs are grounds!). All you need to do is hook the MS up to ground the relay, and the system will do the rest. Which, assuming your original ECM is a 165, would be the green/white wire in terminal A1 of your ECM connector (just get the TPI harness adaptor and a spare ECM connector set and be done with it... The adaptor does all of the wiring for you and everything just plugs in!)

 

Thanks....

What do you mean by the TPI harness adapter and spare ECM connector set?

I am using all of the stock wiring and donating it to the "cause" so to speak.

 

There is an add-on circuit board for the MS that takes the DB32 or whatever it is and converts it to a standard TPI ECM socket...

http://www.diyautotune.com/catalog/m...pcb-p-363.html

This way you don't have to hack up the stock wiring to install the MS and you can even use a dead ECM case to install it in so you don't have to fight with mounting the MS under the dash. You will need to procure a dead ECM or find a set of ECM connectors (inside the ECM) to mount to the adaptor board.

 

Oh yeah... I remember that now. Mine is already "hacked" and being taken to only what I need by a friend who does a lot of megasquirt change overs now...

Any other wires in the C207 I need to use or is it just the green/white for the fuel pump?

 

The dkgrn/wht wire isn't in the C207... The tan/wht wire that crosses the dash from the fuel pump relay and the oil pressure switch (runs to the C208 inside the driver's kick panel and then back to the fuel pump) IS. The dkgrn/wht wire is in the ECM connectors at A1.

As for the C207, you will need most of the wires with the exception of the purple/white wire, which is for the cold start injector system. You can pull the wire out of the ECM harness half of the C207 and use the terminal for something else if necessary. There are a few pink wires in there... 2 are for the fuel injectors (1 per bank) and another is for all of the emissions control stuff (canister purge valve, AIR divert valve, etc). You can use this wire to power the MS off of the ignition, unless you are going to use the factory wire, or another ignition-on accessory.

 

Actually that is not correct...

Board version 3.57, yes is SMD, but is just the main board version and is no different than board version 3.0, other than being SMD, and lack of proto area.

MS3, which can use board version 3.0 an 3.57 (and I believe another) has USB connectivity an SD card logging.

Even with MS3, I'm still finding it hard to find a good reason to switch away from the Delco ECM.

Also, the OEM fuel pump relay is +12V trigger from the ECM, so a relay between the MS an the OEM fuel pump relay is needed, or using a transistor in the proto area (assuming board V3.0) could provide this output.

 

wow, I get so confused on wiring things sometimes!


I have the complete TPI harness out and going with a standalone MS setup. That's why I'm wondering what part of the c207 I need to get the guy doing it for me to tie into those harnesses to plug back into the stock two plugs under the dash so the Fuel pump will come on... as far as everything else MS is controlling it, so do I not need to connect the C207 at all. If I do, what wires, and why?

ECM connecter(as in the one that plugs INTO the ECM?) With the MS being seperate it has to tie into a few wires to operate. ground, power, ignition, fuel pump, etc.

Which ones do I need?

 

If the wiring for the FP relay is in the kick panel and is fed by the tan/white, will the tan/white wire at the c207 fed the green/white wire? If so what signal is the tan/white looking?

Where is the schematic for the fuel pump turn-on relay?

 

There's 2 wires for the relay in the kick panel. 1 is the input for the coil from the ECM. Switch this wire (the green one) with the black one in the relay connector and connect the black one to a pink one somewhere in the harness (the black wire with the pink stripe coming from the EGR connections should do to power the relay). The tan wire is the power coming out of both the relay AND the oil pressure bypass (used when the relay isn't working to power the fuel pump). The rest of the fuel pump relay wiring is under the hood.

 

Well, I used a relay for reversing the on/off of the MS. That being said however, the tan/white wire goes straight to the fuel pump and is a monitoring output from the relay of some kind. I would hook into the green/white wire as GM intended though. No use altering their design too much.

 

Or you can power the fuel pump relay 12v with a switched source and just connect the ground from the relay to the ms. Simple reverse 2 wires on the relay. Thats how i did mine and it works exactly like stock, minus the stock ecm of course. No need for another relay to trigger a relay....

Whoops, just seen how old this thread was, lol

 

The suggestion was so that the OEM wiring did not need to be altered. Also it's safer to use 12V to trigger the relay, which is why GM did it this way to start with. The reason why the fuel relay is triggered with 12V instead of ground is that in the event of a crash, if the ground trigger wire gets pinched, this could cause the fuel pump to stay engaged and if there's a fire this will add fuel to the fire, literally.

 

I understand that. Not like its a pinto, lol. Just letting him know his options, looks like this thread fell off though, once i paid attention to the date, lol.

Is there anyway to add megasquirt install to my thread title? Figured id ask you cause your a mod

 

When i was looking into MS i found a video online of a guy (hes pretty funny) that "dumbs" it down pretty good.

Enjoy lol. This fairmont runs in the 10's on boost with a MS1 i believe haha