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Old 06-04-2021, 12:58 PM   #1
Sliding242
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Default 940 Speedo wiring? 6 pins, lh2.4 swap into 242

I want to strip out the speedometer from a 940 to use in my g80 swap and tuck the speedometer behind the dash to achieve my speed signal problem in my lh2.4 swap. So the speedometer appears to have 6 pins and I am looking for some help determining the ground, 12v, and 2 vss wires (coming from the diff). Has anyone done this? I also have a '92 240 speedometer but see that it operates for the 12 tooth tone ring (my understanding). Maybe someone can shoot me straight
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Old 06-04-2021, 02:11 PM   #2
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Originally Posted by Sliding242 View Post
I want to strip out the speedometer from a 940 to use in my g80 swap and tuck the speedometer behind the dash to achieve my speed signal problem in my lh2.4 swap. So the speedometer appears to have 6 pins and I am looking for some help determining the ground, 12v, and 2 vss wires (coming from the diff). Has anyone done this? I also have a '92 240 speedometer but see that it operates for the 12 tooth tone ring (my understanding). Maybe someone can shoot me straight
Maybe this thread can help?

https://forums.turbobricks.com/showthread.php?t=342812
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Old 06-05-2021, 04:13 AM   #3
Sliding242
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The wiring diagram here http://cleanflametrap.com/speedo7.html is right up my alley, half way down the page for the '93 speedo. I could use a hand deciphering the 6 pins at the top right corner of the diagram. pin1 - ground, pin2 - 48p (pulse from sensor?), pin3 - 16n (?), pin4 - pulse (to ECU?) pin5 - SRL (service light I assume), pin6 - 12p (? maybe also from sensor).

I know I need 12v, ground, 2 wires from sensor and then one to the ECU, anybody make any sense of this?
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Old 06-05-2021, 12:52 PM   #4
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Quote:
Originally Posted by Sliding242 View Post
The wiring diagram here http://cleanflametrap.com/speedo7.html is right up my alley, half way down the page for the '93 speedo. I could use a hand deciphering the 6 pins at the top right corner of the diagram. pin1 - ground, pin2 - 48p (pulse from sensor?), pin3 - 16n (?), pin4 - pulse (to ECU?) pin5 - SRL (service light I assume), pin6 - 12p (? maybe also from sensor).

I know I need 12v, ground, 2 wires from sensor and then one to the ECU, anybody make any sense of this?
Ahh, another gem from Art. The '93 940 speedo pins are:
1 - ground
2 - 48pulse output to ABS (unused for you)
3 - switched +12v power
4 - pulse input from VR differential sensor
5 - ServiceRequiredLight (unused for you)
6 - 12pulse output to LH2.4 VSS

One pin on the rear differential VR sensor gets grounded (it doesn't matter which one), and the other goes to speedo pin 4. If you're running your own wires, just connect the sensor across pins 1 and 4, then ground pin 1.

On the 240 speedos, the Kxxxx number on the face is the number of pulses per mile. For example, 195/60R15 is 833 revs per mile, times 48 tooth per axle rev = 39984, which is close to the normal K39200 gauge. If your 240 speedo is pre-ABS 12-tooth, it will be K9800 or similar; if it's 48-tooth, it will be K39200 or K40182, which could be used to generate LH2.4 VSS (the ABS speedo connectors are slightly different than in my linked instructions).
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Old 06-05-2021, 06:48 PM   #5
Sliding242
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The 240 speedo I have is a K40168.
The 940 speedo I have is from my donor car and is matched with the 48 window tone ring (g80 '93) I swapped into the car.

The simplest route seems to use the 940 speedo.

Just to clarify for my out put signal I should us the 12 pulse output and not the 48 pulse?

Everything in the car now is from the 940t, (ECU, EZK, diff,) dont know how much it matters. Seems like the 940 speedo would suit me best, yet not opposed to using the 240 speedo. I assume if my output to the ECU is not hooked up to the correct pulse I likely wouldnt damage anything anyway. This is boiling down to the last part of my swap so I am stoked to get the last of the wiring worked out (6 years later lol)
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Old 06-07-2021, 09:04 AM   #6
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Either speedo will work. Are you going to mount it in the main cluster? If so, I'd pick the easiest to adapt/mount.

Yes, you want the 12 pulse output for the LH2.4 VSS wire. If it's not connected, you'll have high idle after driving for a bit, but no damage.
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