Any Motec M130 guru's out there - how to do a wiring test?

Cloggie · 02-25-2022, 06:30 PM

Just looking for some help, I am just finishing off a complete wiring harness replacement on my '89 and have gotten to the point where I am connecting my Rasant M130 harness to the 911 harness. Its all connected, grounds are in, positive terminal to the starter (battery)....all good from what I can test so far.

I would like to just plug in the Motec (no engine in the car yet - nothing connected to the Motec harness), plug in my laptop and see whether the Motec boots up and has power etc....just to check the harness.

Then I would like to manually run the fuel pump for a few seconds to make sure that circuit is there. and working.

Is this even possible? I tried plugging in the Motec (no sensors) with my laptop connected and M1 Tune running and it did not detect an ECU with my key in the run position.

I also have been wandering around the M1 software, looking for a place where I can turn the fuel pump on manually....can't find it nowhere

Of course I could have a wiring issue (next on the issue) but I am wondering if the Motec just won't come alive until it has the sensors in place and more connections made.

Any help greatly appreciated...

Douwe

Peter M · 02-25-2022, 11:32 PM

Douwe,
Did Rasant give you a wiring diagram?

If the ECU is getting power you should be able to connect to it with your PC via M1 Tune. Pin A26 should have power when the ignition is on. (A10 and A11 are earths). If you only tried once, it's also worth trying again as it may have just had a "hiccup" when you first tried.

Cloggie · 02-26-2022, 10:08 AM

Quote:

Originally Posted by Peter M

Douwe,
Did Rasant give you a wiring diagram?

If the ECU is getting power you should be able to connect to it with your PC via M1 Tune. Pin A26 should have power when the ignition is on. (A10 and A11 are earths). If you only tried once, it's also worth trying again as it may have just had a "hiccup" when you first tried.

I have power to A26 and grounds look good although I am checking them again.

I reached out to Andrew for the schematic, but I suspect he uses the standard as set by Motec, so I have those at least. Only issue is that the Motec schematics are general annd it would be nice to know exactly which Aux does what and what colour of wires are used....

Thanks for your help.

D.

Cloggie · 02-26-2022, 10:28 AM

....late breaking news.....I went digging through the loom and found there is a ground near each coil pack, so will do the work to get those temporarily connected and see what happens.

The other ground near the ECU checks out fine, so still a little surprised that the ECU does not boot up as the ground is a continuous circuit...any one connection ought to provide an earth.....

D.

Peter M · 02-26-2022, 03:24 PM

Cloggie,
There is something simple that isn't correct. The grounds near the coil packs do not effect your ability to connect your PC to the ECU. As long as you can power up the ECU - even on the bench - you should be able to connect via M1 Tune. Have you downloaded the M1 Tune User manual and followed the connection process detailed on about page 9 or 10 of the manual? I recall there are some trouble shooting tips included as well.

As for the wiring diagram, it might be quicker to pull the Rasant harness out and on to your bench and use your circuit test light to see how they they have configured the auxiliary pins on the M1. It shouldn't take to long as about half the 60 pins are specifically configured (injectors, coils, some sensors like knock) and it is likely only a small number of the the other pins have been used for user configurable purposes.

This will also allow you to clearly see how the relay has been wired to power up you fuel pump.

mikedsilva · 02-26-2022, 03:49 PM

I've only used M130 once... the first time we tried to connect, the network cable we were using was a dud... replaced it and then it worked fine.

Hope it's something as simple as that for you.

Cloggie · 08:06 AM

Quote:

Originally Posted by Peter M

Cloggie,
There is something simple that isn't correct. The grounds near the coil packs do not effect your ability to connect your PC to the ECU. As long as you can power up the ECU - even on the bench - you should be able to connect via M1 Tune. Have you downloaded the M1 Tune User manual and followed the connection process detailed on about page 9 or 10 of the manual? I recall there are some trouble shooting tips included as well.

As for the wiring diagram, it might be quicker to pull the Rasant harness out and on to your bench and use your circuit test light to see how they they have configured the auxiliary pins on the M1. It shouldn't take to long as about half the 60 pins are specifically configured (injectors, coils, some sensors like knock) and it is likely only a small number of the the other pins have been used for user configurable purposes.

This will also allow you to clearly see how the relay has been wired to power up you fuel pump.

Thanks everyone for the help...it is useful and yes, I think it is something simple, probably a forehead slapper once it gets figured out...

So, taking the harness out would be a PITA, possible, but I would rather not as it is integrated with other elements of the 911 harness (AC, tach, alarm system etc etc) so that'd be the last resort. Since there is no interior in the car at the moment and the engine is just a mockup (transmission + engine case) access is quite easy so I can do more checking.

I have contacted Rasant and have asked them for suppport....Andrew has been pretty good so far so I am feeling positive he will be able to get me a schematic and/or help diagnose the issue.

Interestingly there is continuity between the grounds which are intended to be close to the coil packs (4 separate grounds, one for each set of plugs on each bank) and the ECU ground, just not continuity to the main plug going into the ECU (A10/A11).

I must admit I was surprised that there is no "master ground" in the harness. There is a huge wire connecting the whole harness to the positive (starter terminal), but the only grounds are a small one near the ECU and 4 small ones for each bank/plug set. I would have expected a big honking ground somewhere in the harness.....hopefully it did not get left out when Rasant built the harness, this is a very custom and mistakes happen.

Will keep you all informed and thank you for the help, the validation and ideas are invaluable.

D.