540i harness clarification needed

[84318i]

Hi,

I don't have a 530/540 parts car that I can quickly reference, and could use some double-checking so I don't burn the harness up

Could someone help identify these, I've used a DMM and the big round lug out of the 3 appears to be ground, but the other 2 don't show continuity to the positive solid red that is further up near the relays.

These 3


This guy is by the DME and Cluster temp senders if I go by memory, is this ground ?


Pretty sure these two are starter wires


Now, these 3 are identical, one is probably TPS, Air temp, and ? Which one is what ?
They are on the passenger front side.

[84318i]

Anyone with a 540i willing to take a look at these and snap a photo ?

[moroza]

The first one should be ground. Not sure about the second (ground on the rear coolant manifold?) or the third; I'll get back to you on that. Starter wires are white and yellow cloth, and one is square. The three identical plugs differ by their color, which should match what they plug into - one for the IACV, one for the TPS, and one for the intake air temp.

[84318i]

Ok figured out most of these but not all.

The 3 ring style terminals coming out of the harness on the passenger side are as follows
- big one is ground
- one with red end is positive
- 3rd one is marked as 30h , black wire with green stripe .

I looked at the routing on e34 530i car and the 3 go to a little junction box where the battery cable and starter cable attach . The 30h wire connects to some other wire that goes on the chassis side ...


Now , the front passenger side I have these

- icv
- air temp
- maf
- throttle position

And I have two more left, on 530 one goes to the sensor that sits on top of the manifold on the passenger side and has vacuum line going to some smog pump thing that my m60b40 does not have ...can this just be left unplugged ?

Possibly one more left , did 530 have some additional sensor near throttle body ?

Basically I am using a 530 manual harness on 540 m60b40 engine ...with correct dme .

[moroza]

And I have two more left, on 530 one goes to the sensor that sits on top of the manifold on the passenger side and has vacuum line going to some smog pump thing that my m60b40 does not have ...can this just be left unplugged ?

Possibly one more left , did 530 have some additional sensor near throttle body ?

Basically I am using a 530 manual harness on 540 m60b40 engine ...with correct dme .

Later M60 cars had a smog pump, but I have not worked on one of those. If the DME isn't expecting a smog pump, I don't forsee problems like a CEL.

Some (early and late) had a second throttle body for the ASC, with its own TPS.

[84318i]

Can the second throttle body connector and smog pump thing be ignored or do I need to use another engine harness ?

Think of 540i stock m60b40 engine configuration but it's one throttle body driving by cable only .

I have this in my e30 , and I thought the harness i purchased was from a 540i manual car but looks like it might be from 530i or maybe it's from 540 since as you said some of those had the additional smog pump ?

E34 530i parts car I looked at today to see where these plugs go had a big vacuum / hose going to the airbox ...mine doesn't have that.

Also, 30h is a starter wire isn't it? Does the e34 530i not have a starter wire on the x25 connector since I am seeing it as a ring terminal in that group of 3 wires (ground, positive , and 30h) at the back of the harness on the passenger side.

[moroza]

Can the second throttle body connector and smog pump thing be ignored or do I need to use another engine harness ?

I'd expect an ASC light from ignoring the former and a CEL from the latter, but the car should run fine.

I have this in my e30 , and I thought the harness i purchased was from a 540i manual car but looks like it might be from 530i or maybe it's from 540 since as you said some of those had the additional smog pump ?

My understanding is that the 530iM and 540iM harnesses are identical. They differ from their automatic counterparts only in the wires related to the transmission. I've seen later B30's with the smog pump, but never worked on one and can't confirm that B40's had it too.

E34 530i parts car I looked at today to see where these plugs go had a big vacuum / hose going to the airbox ...mine doesn't have that.

Probably for the smog pump.

Also, 30h is a starter wire isn't it? Does the e34 530i not have a starter wire on the x25 connector since I am seeing it as a ring terminal in that group of 3 wires (ground, positive , and 30h) at the back of the harness on the passenger side.

30h appears to be a signal wire from the starter to the OBC, IHKR, and GM. I don't know what X25 is. M60 starter wiring had three variations depending on production date, but none of them talk to the DME.

Go here, download at least the 1994 diagram, and see section 1240.

[84318i]

I'd expect an ASC light from ignoring the former and a CEL from the latter, but the car should run fine.



My understanding is that the 530iM and 540iM harnesses are identical. They differ from their automatic counterparts only in the wires related to the transmission. I've seen later B30's with the smog pump, but never worked on one and can't confirm that B40's had it too.



Probably for the smog pump.



30h appears to be a signal wire from the starter to the OBC, IHKR, and GM. I don't know what X25 is. M60 starter wiring had three variations depending on production date, but none of them talk to the DME.

Go here, download at least the 1994 diagram, and see section 1240.

Thanks !

My concern is with the extra connectors on the passenger front side for the smog pump and asc throttle body as I am not using those . Maybe I'll need to find another Harness without these on it as I can't have any lights on the dash or stored in the dme .

30h seems to go to x79 and as you said power others modules that I can ignore .

[moroza]

You would not have warning lights just from extra wiring hanging around; there needs to be a module that expects something at the other end of that wiring.

[84318i]

Makes sense! Thanks moroza, I was afraid it would be an issue so hopefully there won't be any complications from ignoring the second throttle body connector and the 530i smog pump thing (what's the proper name for it?).