DME Harness Modification
 

I have a Carrera 3.2 setup and as part of my restoration, I would like to make the DME harness modular. In other words, split it into front (engine bulkhead to DME under driver's seat) and rear (bulkhead to engine) parts that are linked through a bulkhead connector such as the following:

http://www.tweakdperformance.com/hos...s/milspec3.jpg

Does anyone forsee any issues with this? The only thing I can think of is the shielding for the two VR sensors reading the flywheel. There will effectively be a (very) short length of unshielded wires. I've been told this will not affect the signal, but thought I'd check with some of the sparkies on the forum.

I have done Motec M84 harnesses with a bulkhead connector..no running issues with it.

A good place to source the connectors is https://www.wirecare.com/category/connectors-terminals/deutsch-connectors

The one I used was a Deutsch HD 30. The wire gauge or pin size count is different depending on how many connector pins you decide on. The one I used was a 35 pin, which has 3 pin for larger gauge wire like 14-16, and the rest work with 18-20ga. The Deutsch connector pins are wonderful to crimp if you have the special tool, (which is not cheap to buy) but Wirecare will rent with a weekly rate.

You can also get dust boots, large washer and nut for the bulkhead connector. I remember those being ordered separate.

Thanks! Do you think there is any advantage to splitting the loom into separate connectors to minimize noise? For instance, one for lower voltage and one for higher voltage signals?

The 3.2 Carreras are known to be bullet proof so any "advantage" would be theoretical as they don't have an issue with it. There isn't any high voltage in the harness anyway. Obviously there is 12V but the sensors are all at 12V or less. For example the crank sensor signal is 2.5V.

Now if you go and make a major modification so there is real voltage in there then all bets are off.

The advantage of this system to me is simply to make it easier to install/remove the loom in future (as opposed to dragging the whole loom through the hole in the chassis).

Also, I should probably have said "high current" - for example, power feeds to coils and injectors - versus low current signals from sensors.

Other than painting the car, why would you have to remove the loom?

I'm putting together a Megasquirt-based ITB system which will have a fresh wiring loom. I want to keep the Motronic setup as a backup in case things go tits up, so I'd like to be able to install/remove the factory loom more easily.

It shouldn't be a problem, and I've said on someone else's post, put the VR wires in the middle of the cluster, so the rest of the wires act as a Faraday cage if you're concerned about noise.

Also, I have a 40 pin military cannon plug I might sell since I was going to do the exact same thing with my MS harness.

But, I figured I don't drop the engine enough to justify.

It only takes a few minutes to disconnect all the plugs.