Mustang MonthlyHow To Engine
How to Troubleshoot Neutral Safety Switches
Pesky no-starts can often be traced to this easy fix and adjustment
Classic Mustangs tend to leave unsuspecting motorists stranded because the engine won't turn over, leaving owners at the mercy of repair shops that try to sell them a battery, starter, solenoid, or even a charging system when the only problem is a bum neutral safety switch. Half the time, all the neutral safety switch needs is a simple adjustment.
The neutral safety switch, which is mounted on the side of C4 and C6 transmissions and at the shifter with FMX models, is there to do two things—prevent you from starting your Mustang while it is in gear and activating the back-up lights while in reverse. Mustangs without back-up lights won't have the back-up light provision and plug. Neutral safety/back-up light switches are basically the same on C4 and C6 from '65 to '73 with the exception being harness length and plug design. The FMX's neutral safety switch is simple with adjustment instructions located on the switch itself.
A complete line of neutral safety switches are available from Virginia Classic Mustang. Mustangs Etc. has both reproduction and new-old-stock Ford neutral safety switches.
|Original Ford Part Number (7A247 Base)||Transmission Type||Specifics||Location||Description||Revised Part Number (7A247 Base)|
|C4AZ-C||C4||'65-'67 Before 12/15/66||Transmission||Two Duplex Plugs|
|C7ZZ-B||C4||'67 from 12/15/66||Transmission||One Quad Plug||C9ZZ-B|
|C7ZZ-C||C4||'68-'69||Transmission||One Quad Plug||C9ZZ-B|
|D0ZZ-A||C4||'70-'73||Transmission||One Quad Plug with taller standoffs to clear locking column lever.||D1FZ-A E0DZ-A|
|C6AZ-A||C6||'67 before 12/15/66||Transmission||Two Duplex Plugs|
|C7ZZ-A||C6||'67 from 12/15/66||Transmission||One Quad Plug||C9ZZ-B|
|C7ZZ-D||C6||'68-'69||Transmission||One Quad Plug||C9ZZ-B|
|D0ZZ-B||C6||'70-'72 before 12/1/71||Transmission||One Quad Plug with taller standoffs to clear locking column lever.|
|D2ZZ-C||C6||'72-'73 from 12/1/71||Transmission||One Quad Plug with taller standoffs to clear locking column lever. Additional plug for seatbelt interlock.|
|C9ZZ-A||FMX||'69-'72 before 12/1/71||Shifter||One Quad Plug with single pin plug.||C9ZZ-C D2ZZ-B|
|D2ZZ-A||FMX||'72 from 12/1/71 to 1/5/72||Shifter||One Quad Plug with additional duplex plug and single pin plug.||D2ZZ-B|
|D2ZZ-B||FMX||'72-'73 from 1/5/72||Shifter||One Quad Plug with duplex plug and single pin plug.|