The 7mge (or 7mgte) ECU also had a speed sensor input, and this signal came from the dash.
If/when you get the speedo in the dash working you'll be able to send the signal that went to the stock ECU to the new 1JZ ecu
The wire is marked as "SPD" (shown on the below diagram taken from the TSRM for 7mge)
http://www.cygnusx1.net/Supra/Librar...aspx?S=FI&P=31
Also:
http://www.autoshop101.com/forms/h36.pdf
Cheers
Wilbo
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