DTC P1510: Pcm Back-Up Power Supply Malfunction

Measure voltage (backprobe) between ground and White wire between PCM 26-pin harness connector C21 terminal No. 14 (Esteem 1.6L & Swift) or PCM connector terminal E92-13 (Esteem 1.8L) with ignition off, then with engine running. Both readings should be 10-14 volts. If readings are not as specified, repair open in White wire between underhood relay/fuse block and PCM harness connector. If readings are as specified, check for poor connection at PCM. If connections are okay, replace PCM.