LS Swap Gauge Wiring

[FLBMWM3]

I am at the point where I would like to wire up my E36 gauges to work with my LS swap. Below I have highlighted the wires on the gauge cluster schematic that I think I need to connect. If anyone could confirm that what I have shown is correct I would greatly appreciate it. As always thank you for your help!
Gauge Cluster Wiring Diagram.jpgGauge Cluster Wiring Diagram 2.jpg

[wbrentr]

Only signal that the LS PCM needs to send to the BMW cluster is the tach. Connect that to X20 black wire, forgot the pin. You will need a BMW coolant temp sensor, but the wiring is dependent on application.

**There are other signal wires to be connected, this refers to the instrument cluster only.

[FLBMWM3]

So the wiring diagram I have lists the connectors as Conn A, Conn B, and Conn C. Does one of those equate to X20? Also I should have mentioned that I have Zero BMW wiring left in this car. The engine has a stand alone harness, and I used a separate body harness for all of the lights. Currently I have the BMW connectors coming off of the back of the cluster, and my plan was to make a harness to provide power to the cluster, and then tie in the signals for the speedometer, tach, coolant, and fuel. I do already have the BMW coolant sensor in the passenger side head, and wires pulled back to the gauge cluster.

[motorV8ed]

I find the official BMW electrical diagrams give a lot of info that the Bentley manual you have does not: http://www.wedophones.com/Manuals/BM...g%20Manual.pdf

[FLBMWM3]

Thank you. It looks your link already answered one of my questions.
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[motorV8ed]

Thank you. It looks your link already answered one of my questions.
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Awesome!

Here is another tip: pdf versions for later cars are hot-linked and searchable. However, of course, those manuals are not for your car! However, there is a lot of commonality. So one strategy is to find the oldest E36 manual that is searchable, find the wiring section you want, then go to that section for the plain pdf appropriate for your car.

Also, have you reviewed this thread:

http://forums.bimmerforums.com/forum...LSx-E36-Wiring


These posts in that thread are particularly useful (although do not directly address your particular question):
http://forums.bimmerforums.com/forum...6#post24774946
https://www.bimmerforums.com/forum/s...9#post26813259

EDITED TO ADD: I just re-read your earlier post, and realize that the thread I pointed you to is not that useful for your particular situation. I am leaving the links in there for others, however.

[FLBMWM3]

Thank you very much.

I think I have everything wired up correctly, and I am gonna test the gauges today. One question I had was regarding the wiring of the fuel level sensors. How can I tell which sensor is sensor I and which is sensor II, or does it even matter since they are wired in series and have the same ohm range? I hooked the fuel sensors up yesterday to the gauge cluster and provide power and ground to the cluster, but the fuel gauge never moved. I have over 10 gallons of gas in the car so it should be moving up. Any thoughts or help with the fuel gauge would be greatly appreciated.
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[motorV8ed]

You can tell which is which by cross-referencing the connector numbers (X1241 and X679). Near the end of the manual, there is a text description and a schematic diagram showing where the X-indicated connectors are. I didn't bother looking at your year, but for my year (1999), X1241 (Sensor I) is located under the left-hand side of rear seat, and X679 (Sensor II) is located under the RH side. (I would be very surprised if it were different in your year.)

But, as you say, it doesn't seem that it should make any difference which order they are wired...

[FLBMWM3]

So I checked the ohms on the sensors. The one behind the drivers seat shows 20ish ohms. The one behind the passenger seat shows 190, then 180, then zero in rapid succession. Really didn't want to have to pull the fuel sender, but it looks like that is the next step. I fired the car up it my tach is working so that is good news. It is raining here today so I can't see if the speedo works yet.

[FLBMWM3]

Pulled the fuel sender, and everything looked good. No broken or disconnected wires. I checked the resistance again, and had a steady 80 ohms when I put the sender back in the tank (maybe something was stuck who knows). I checked the resistance all the way back to the X271 connector, and the resistance was the sum of the two sending units. However when I plug the connector into the gauge cluster I still get nothing. Is it possible that the gauge is bad, and is that a common issue with the E36's?

Also I installed the BMW coolant sensor in the passenger side head and wired everything up, but I am not getting any temp readings.

Outside of that the speedo seems to work, and the tach does as well but it seems to be about 500 RPM off from what I am reading on my OBDII gauges.

I welcome any thoughts or input. Thanks.

[FLBMWM3]

I got all of the gauges work (Fuel, Speed, Tach, and Temp). Below are the pins that were used. Hope this helps someone else.
E36 LS Gauge Wiring.JPG

[motorV8ed]

Glad you were able to work that out.

For me, integrating the wiring was one of the hardest parts of the swap, even though what I had to do (unlike you) had been worked out by others.

[FLBMWM3]

Thank you. The next wiring hurdle is to build a body harness to run all the lights using the BMW factory switches. Shouldn't be to bad.