Operation CHARM: Car repair manuals for everyone.
Manuals through 2025 now available!

Our trusted friends have launched a new website named LEMON, which has newer manuals. It also contains all the CHARM manuals.

LEMON is the spiritual successor to CHARM, I recommend you try it!

Link: lemon-manuals.la or lemon-manuals.org.ua

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Speed Signal Test

Speed signal test:





Electronic Instrument Cluster Only
1. With wheels raised and vehicle speed at 30 m.p.h., measure the AC voltage of the speed signal at the speed control amplifier connector, Fig. 10.
2. If reading obtained is less than 6 volts, disconnect speed control amplifier and repeat measurement.
a. If voltage is greater than 6 volts, replace speed control amplifier and retest.
b. If voltage obtained is less than 6 volts, check circuit 150 back to speedometer stud on the cluster for an open or short. If circuit is satisfactory, replace speedometer electronics and retest. If an open or short exists, repair as necessary.
3. If reading obtained is more than 6 volts, measure the DC component at the speed control module.
a. If voltage obtained is greater than 1 volt, replace speedometer electronics and retest.
b. If voltage obtained is 1 volt, speedometer circuit is satisfactory. Proceed with ``Speed Control Diagnosis.''