Mazda 6 Workshop Manual page 183

DTC P1391 Glow plug circuit low input
• Glow plug relay malfunction
• Melt or burnt glow fuse
• PCM malfunction
• Glow plug malfunction
• Connector or terminal malfunction
POSSIBLE
• Open circuit in wiring harness between glow plug relay terminal A and PCM terminal 86
CAUSE
• Open circuit in wiring harness between glow plug relay terminal C and PCM terminal 68
• Open circuit in wiring harness between glow plug relay terminal B and body GND
• Open circuit in wiring harness between glow plug relay terminal D and GLOW FUSE
• Short to GND circuit in wiring harness between glow plug relay terminal A and PCM terminal 86
• Short to GND circuit in wiring harness between glow plug relay terminal C and PCM terminal 68
4
GLOW FUSE
GLOW PLUG RELAY
5
5
GLOW PLUG RELAY
WIRING HARNESS-SIDE CONNECTOR
B
D A
C
ON-BOARD DIAGNOSTIC
D
A
GLOW
PLUG
B C
10
26 25 24 23 22
52 51 50 49 48
78 77 76 75 74 73
104 103 102 101 100
13
12
11
86
11
68
8 9
PCM
WIRING HARNESS-SIDE CONNECTOR
21 20 19 18 17 16 15 14 13
47 46 45 44 43 42 41 40 39
72 71 70 69 68 67 66 65
99 98 97 96 95 94 93 92 91
PCM
12 11 10 9 8 7 6 5 4 3
38 37 36 35 34 33 32 31 30 29
64 63 62 61 60 59 58 57 56 55 54
90 89 88 87 86 85 84 83 82 81
F2–171
F2
2 1
28 27
53
80 79