Mazda MX-5 Miata Sport 2007 Manual page 2057

2007 ENGINE PERFORMANCE Symptom Troubleshooting - MX-5 Miata
Finding Irregular Signals
While referring to ON-BOARD DIAGNOSTIC TEST [LF] , use the PID/DATA monitor and record function
to inspect the input signal system relating to the problem.
1. Start the engine and idle the vehicle. You can assume that any signals that are out of specification by a
wide margin are irregular.
2. When recreating the problem, any sudden change in monitor input signals that is not intentionally created
by the driver can be determined as irregular.
Locating the Source Of Unusual Signals
CAUTION:
Variable Resistance Type 1 (TP Sensor and EGR Boost Sensor)
2007 Mazda MX-5 Miata Sport
Compare the M-MDS or equivalent monitor voltage with the

measurement voltage using the digital measurement system
function. If you use another tester, misreading may occur.
When measuring voltage, attach the tester GND to the GND of the

PCM that is being tested, or to the engine itself. If this is not
performed, the measured voltage and actual voltage may differ.
After connecting the pin to a waterproof coupler, confirming

continuity and measuring the voltage, inspect the waterproof
connector for cracks. If there are any, use sealant to fix them. Failure
to do this may result in deterioration of the wiring harness or
terminal from water damage, leading to problems with the vehicle.