DTC P1500 - Engine Start Signal Circuit Malfunction
WARNING: This page is about a different car, the 1996 Suzuki Swift. However, it is still accessible from the selected car via links, so may be relevant.
Using a voltmeter, measure voltage (backprobe) between ground and PCM harness connector "B", terminal No. 16 while cranking engine. Reading should be 6-10 volts. After engine starts, voltage should drop to zero. If reading is as specified, check for poor connection at PCM. Repair as necessary. If connections are okay, replace PCM. If reading is not as specified, Repair open Black/Yellow wire between starter and PCM. Retest system.