Engine Loom Questions

guye · #1 (**permalink**) 07-26-2015, 07:06 AM

Hi guys.

I'm taking on my loom, and have a few questions perhaps some of you can help with please.

Context: I am talking about my L77 GM 6.0l with an E38 ECU. From a 2013 delivery SS Redline Commodonor. Manual (so no DoD). I've got the engine loom, ECU , accelerator pedal, and MAF from the donor.

So, I've pulled out all the redundant wires from my loom, and am down to the last few pins off the ecu now. The several questions I have are as follows:

Radiator Fan. The ecu has a low speed and a high speed fan wire. I'm only running a single speed, single fan, so do I just use the low speed fan and ignore the high speed?
Fuel level and pressure sensors. I believe some later ecu's use this to adjust mixture for ethanol and petrol based on these settings. Do I really need to run these, as I've only got a fuel level sender and was planning on using that for the fuel gauge. Or is this something I can fix when I get the ECU reprogrammed?
Can anyone confirm the ECU pins I need to wire to create the OBD2 socket?
Cruise control? I presume I need another unit to make this work? Or do some of the ECU pins do this too?

Aussie Mike · #2 (**permalink**) 07-26-2015, 08:16 AM

On the LS1 the low speed fan is set up to come on with the AC. The High speed fan is the one that is temp controlled. That being said the temp it kicks in at is too high so needs to be adjusted down with HP tuners or similar.

Cheers

guye · #3 (**permalink**) 07-26-2015, 08:20 AM

Sounds logical Mike. Is prob the same then. Does the LS1 use an E38 with 58tooth reluctor too?

Aussie Mike · #4 (**permalink**) 07-26-2015, 08:28 AM

Different generation of ECU for the LS1 but I reckon the philosophy around the high and low speed fan is probably the same.

On the LS1 there was only a high speed output on the ECU. The low speed was done by the BCM.

Hopefully an expert can chime in here and let us know if both outputs on the E38 ECU run off temp or if the low speed runs off an AC trigger.

It'd be nice if they both did as you could use a dual SPAL fan setup from a late model Falcon or similar and have the two fans triggered independently.

guye · #5 (**permalink**) 07-26-2015, 09:12 AM

Yeah, my source (lt1swap.com) says that's exactly what he recommends. Dual speed fans off the Ford Taurus. And he wires them in using those two lo/hi pin outs from the ECU.

See half way down this page: Wiring Harness Information

'Course I've only got a single speed fan. Hence I'm thinking the low pin would be ok and we just need to program the temp setting. But the fan coming on a bit early it probably better than too late in the interim, methinks!

DaveW · #6 (**permalink**) 07-26-2015, 02:45 PM

Hi Guye,
Not up to my loom yet, so cant help there, but i am going through the Cruise Control thing at the moment.
Forget everything after VY, they are dependent on the BCM, but VT to VX is a stand alone Delphi unit only requiring a speed signal from the ECU (e38 has this output)..plus the switch wiring.
Gregg has his up and running and the simple wiring diagram to get it running.

Dave

Dave

DaveW · #7 (**permalink**) 07-26-2015, 02:49 PM

Except, i forgot you probably have DBW on that beast, so forget everything i said unless you are converting to cable.... whoops

gjkrv8 · #8 (**permalink**) 07-26-2015, 03:50 PM

Quote:

Originally Posted by DaveW

Except, i forgot you probably have DBW on that beast, so forget everything i said unless you are converting to cable.... whoops

You beat me too it Dave.

Guy there are a few aftermarket Cruise control kits for DBW throttle - I'll email you some links as when I was looking for mine I kept on coming across good DBW versions rather than cable ones. (I ended up using the stock LS1 Cruise control module which works a treat)

FWIW - I have a single speed shrouded FAN running off the HS FAN output etc (with modified temp turn on etc) and it works a dream. Driven in Melb traffic on a a hot day and all good. The only overheating thing in the car was the driver :-)

I reckon a single HS FAN output fan/relay etc is simple and effective using the KISS principle :-)

Cheers

gregg

Tenrocca · #9 (**permalink**) 07-27-2015, 01:50 AM

I have the same setup as gregg and its all good - Run of the HS Pin. LS not used. Make sure you get them to switch off the AC in the tune, otherwise the "AC not found" fault code will trigger the fan to run all the time.

Cheers

Tenrocca · #10 (**permalink**) 07-27-2015, 02:00 AM

Also, for OBD2:

Can Lo: Pin 27 to 14 on OBD2
Can Hi: Pin 28 to 6 on OBD2

Cheers

Tenrocca · #11 (**permalink**) 07-27-2015, 02:03 AM

If you PM me you email I can you send you an excel spreadsheet with all the wiring details I know (Mine is L76 with E38 but I imagine it should be pretty much the same).

Cheers

guye · #12 (**permalink**) 07-27-2015, 08:08 AM

Awesome guys, all useful thanks. I am running the DBW. Russell sent me one link, Gregg, but all alternatives greatly appreciated.

I'm guessing they just interrupt the GMLAN signals or TAC signals, so was kind of hoping I could work it out with some help. Not that I mind buying something, just that its all about trying to work it out myself (kind of, with some help!).

PM sent Tenrocca as you are right - the L98 is essentially the same!