Central Processing Unit (CPU)
Locate CPU unit behind left kick panel. Leave CPU connector attached. Using DVOM, measure voltage at specified terminals of CPU connector (backprobe connector). SeeFig 1
. See CPU CONNECTOR PIN VOLTAGES & CONTINUITY
. Disconnect CPU connector and check continuity at specified terminals. If voltage measurements or continuity are not as specified, check related components and wiring harnesses. If related components amd wiring harnesses are okay, but system is still not functioning properly, replace CPU.
Courtesy of MAZDA MOTORS CORP. CPU CONNECTOR PIN VOLTAGES & CONTINUITY
| Terminal |
Desired Condition |
| 16-Pin Connector "A" |
| "A" (Hood Switch) |
| Hood Closed |
No Continuity |
| Hood Open |
Continuity |
| "B" (Starter Cut Relay), Constant |
Battery Voltage |
| "E" (Rear Door Switch) |
| Rear Doors Closed |
No Continuity |
| Any Rear Door Open |
Continuity |
| "F" (Horn Relay), Constant |
Battery Voltage |
| "G" (CPU Ground), Constant |
Continuity |
| "H" (Key Reminder Switch) |
| Key Inserted |
Battery Voltage |
| Key Removed |
No Voltage |
| "J" (15-Amp ROOM Fuse), Constant |
Battery Voltage |
| 16-Pin Connector "B" |
| 1B (Trunk Key Cylinder Switch) |
| Locked |
No Continuity |
| Unlocked |
Continuity |
| 1C (Headlight Relay) |
| Headlights Off |
Battery Voltage |
| Headlights On |
No Voltage |
| 1D (Trunk Compartment Light Switch) |
| Trunk Lid Closed |
Battery Voltage |
| Trunk Lid Open |
No Voltage |
| 1E (Flasher Unit) |
| Hazard Switch Off |
Battery Voltage |
| Hazard Switch On |
No Voltage |
| 1G (Door Lock Timer Unit) |
| .4 Sec. After Door Locked |
No Voltage |
| Other |
Battery Voltage |
| 1I (Door Lock Timer Unit) |
| .4 Sec. After Door Unlocked |
No Voltage |
| Other |
Battery Voltage |
| 1P (Keyless Unit), Not Operating |
5 Volts |
| 20-Pin Connector "C" |
| 2D (Passenger's Door Switch) |
| Door Closed |
No Continuity |
| Door Open |
Continuity |
| 2G (Trunk Lid Opener Relay) |
| .27 Sec. After TRUNK Pressed |
No Voltage |
| Other |
Battery Voltage |
| 2H (Driver's Door Lock Link Switch) |
| Locked |
5 Volts |
| Unlocked |
No Voltage |
| 2L (Door Lock Switch) |
| Locked |
2.5 Volts |
| Unlocked |
No Voltage |
| Other |
5 Volts |
| 2M (Security Light) |
| Light Off |
Battery Voltage |
| Light On |
No Voltage |
| 2P (Passenger's Door Key Cylinder Switch) |
| Locked |
2.5 Volts |
| Unlocked |
No Voltage |
| Other |
5 Volts |
| 2R (Driver's Door Key Cylinder Switch) |
| Locked |
2.5 Volts |
| Unlocked |
No Voltage |
| Other |
5 Volts |
| 2T (Driver's Door Switch) |
| Door Closed |
No Continuity |
| Door Open |
Continuity |
| 16-Pin Connector "D" |
| 3B (Keyless Unit), Not Operating |
5 Volts |
| 3C (Door Lock Timer Unit) |
| .4 Sec. After UNLOCK (Driver) Pressed |
No Voltage |
| Other |
Battery Voltage |