420SEL (126.035) V8-4.2L (116.965) (1986)
4 If not, remove instrument cluster and pull off 4-point coupler (2).
5 Connect a voltmeter (measuring range 0-3 volts, AC) to jack 1 and 3 and repeat test.
If the needle on voltmeter deflects when the screwdriver is pulled away from transmitter, the transmitter with its line is in order and the E-tacho is
defective. If the needle is not deflecting, the transmitter is defective or the line to instrument cluster is interrupted.