The Dianostics plug is positioned at the rear of the engine bay on the passengers side on the cavalier
Dis-engage the diagnostics plug from its socket.
It has 10 pins.
[J ] [A] ----- || Bridge pins A&B together. You can use a paper clip to do so (see image below)
----- ||
[H] [C]
[G] [D]
[F] [E]
Short pins A & B to read the engine ecu codes. Brown & Brown/yellow
Start the engine (*** see below ***) management warning light will start to flash as follows.
The code 12 is first flashed three times, this is a marker.
If a code is stored it is then flashed three times.
The code 12 is then flashed three times, this is a separator.
If a 2nd code is stored it is then flashed three times or the first code is repeated.
The code 12 is then flashed three times, this is a separator.
etc
UPDATE by Robsey.
On my cars, the flash code " 1...2" is only flashed up at the start / end of the whole sequence. . Not between each individual code.
Also - for most engines, just turn on ignition. Do not start the engine.
Once all codes have been displayed, stop engine and remove wire.
To clear codes you should disconnect the battery for a minimum of
10 minutes and then re-connect.(this doesnt always work on Ecotec models though for some reason but fixing the fault will put out the light) This also has the effect of resetting
the ECU parameters to their defaults and forces the adaptive learning
circuits to start again. Within approx. 200 miles the ECU will have
adapted.
12 Diagnosis Initiation / separator
13 Oxygen sensor - open circuit
14 Coolant temperature sensor - voltage low
15 Coolant temperature sensor - voltage high
16 Knock signal circuit - no voltage change (on v6; rear bank)
17 Knock signal circuit 2 - no voltage change (V6 front bank)
18 Knock control module (ECU)
19 Incorrect RPM signal (Crankshaft sensor - incorrect signal)
21 Throttle position sensor - voltage high
22 Throttle position sensor - voltage low
23 Knock sensor - out of range
24 Speed Sensor (MPH)
25 Injector 1 - voltage high
26 Injector 2 - voltage high
27 Injector 3 - voltage high
28 Injector 4 - voltage high
29 Injector valve 5 - voltage high (Fuel pump relay voltage low)
31 No engine RPM signal Engine not running (Crankshaft Sensor - No Signal)
32 Fuel pump relay - voltage high
33 Map Sensor (Voltage High)
34 Map Sensor (Voltage Low)
35 Idle Control Valve Stepper Motor (No Idle Speed Control)
36 Incorrect RON/Octane setting - Damaged RON plug or bad connection.
37 Engine self-diagnosis (fault code light) - Low voltage
38 Oxygen circuit - voltage low (weak)
39 Oxygen circuit - voltage high (rich)
41 1 gear ident switch - voltage low C20LET OR EST Line Coil Cylinder 2 & 3 (Voltage High) M2.8 / XEV
42 1 gear ident switch - voltage high C20LET OR EST Line Coil Cylinder 1 & 4 (Voltage High) M2.8 / XEV
43 Linear EGR System XEV
44 Oxygen circuit - voltage low (weak)
45 Oxygen circuit - voltage high (rich)
47 Linear EGR Position XEV
48 Battery voltage - low
49 Battery voltage - high
51 ECU faulty (memory failure)
52 Check engine light - voltage high
53 Fuel pump relay - voltage low
54 Fuel pump relay - voltage high
55 ECU faulty (Hardware fault)
56 Idle air control - voltage low (or high !?!)
57 Idle air control - voltage high (or low !?!)
61 Fuel tank vent valve - voltage low
62 Fuel tank vent valve - voltage high
63 EST Line Coil Cylinder 2 & 3 (Voltage Low) M2.8/XEV
64 EST Line Coil Cylinder 1 & 4 (Voltage Low) M2.8/XEV
65 Idle CO potentiometer - voltage low
66 Idle CO potentiometer - voltage high
67 Idle position switch - voltage low (idle position switch not opening)
69 Intake air temperature - voltage low
71 Intake air temperature - voltage high
72 Full position switch - voltage high (full load not opening)
73 Air flow sensor - voltage low
74 Air flow sensor - voltage high
75 Torque control - voltage low (Transmission Switch)
76 Torque control - continuous (Transmission Switch)
79 Full load inhibitor - voltage low (Traction Control Signal)
81 Injector valve 1 - voltage low
82 Injector valve 2 - voltage low
83 Injector valve 3 - voltage low
84 Injector valve 4 - voltage low
85 Injector valve 5 - voltage low
86 Injector valve 6 - voltage low V6
87 A/C cut-off relay - voltage low
88 A/C cut-off relay - voltage high
92 Cam shaft sensor failure XEV
93 Hall sensor - voltage low (Quad Driver Module)
94 Hall sensor - voltage high
95 Hot start valve - voltage low
96 Hot start valve - voltage high
97 Ignition/Injection cut off - voltage high (Traction Control Signal)
113 Boost control out of range
114 Boost pressure Idle above upper limit
115 Boost pressure Full below lower limit
116 Boost pressure Full below upper limit
117 Wastegate valve - voltage low
118 Wastegate valve - voltage high
