j894
10-13-05, 12:45 AM
Service Engine Soon: Why?!?
http://www.troublecodes.net/articles/AT/palm/service_engine_soon_light_on.JPG
WTF?!?!?
So your driving down the road minding your own business, you happen to look
at your instrument panel and to your suprize the "Service Engine Soon" has
appeared out of no where. If your truck is pre '95 year model, it is most likely
equiped with On Board Diagnostics 1 (OBD1). Instead of going to a Dealer
and/or paying out the ying-yang for a professional to do it with an expensive
scanner, check out your stationary supplies first.
http://img115.exs.cx/img115/7869/tn_PaperClip.jpg
This aint no super-duper code scanner, but when used correctly it works and
gives you the same results.
http://www.vanforum.net/Extern/Technik/Images/Bilder/Connector-1.jpg.
This is an illistration of your Assembly Line Diagnostic Lead (ALDL) Connector.
You might have seen this right near the bottem center of you dash, or under
it around the steering wheel area. Locate this on your vehicle then we could
begin checking the codes.
The above is for most GM vehicles 1981-1995. Starting in 1994 the OBD2
system and connector were phased in with full implementation in 1996 (the
above connector is OBD1).
Once you've found your ALDL connector your going to need to bend that
paper clip in to a "U" like shape. With the ignitionoff,
insert the paper clip into terminal "A" & "B" to jump them. Get a pen &
a piece of paper or something to right on, cause you might need it.
Next, Turn your ignition into the ON postion (just before it would normally
start), DO NOT START!
At this point with your undivided attention observe the S.E.S. light on the
dash board, it will begin to blink number codes in a morse code fashion.
EX.
http://www.s10planet.com/gallery/uploads/51/SESsmall.JPG (Pause) http://www.s10planet.com/gallery/uploads/51/SESsmall.JPG http://www.s10planet.com/gallery/uploads/51/SESsmall.JPG
......Blink..........................Blink........ .Blink
.....(One)................................(Two) = 12
As you can see it's not that hard to figure out...
That flashing sequence is Code # 12
Each code will flash its sequence 3 times before moving to the next code.
When checking checking them, Code 12 will always come up first to
let you know its in diagnotic mode. This will also be the last code you
see which indicates there are no others after it(and it will start over).
Even if your SES light doesn't stay on, each code is stored in memory
for a number(50 ?) of ignition cycles each time the fault is detected.
So you can go back and check even if the light went out by itself.
If you repair the problem the codes can be cleared by disconnecting
the battery, or pulling the ECM fuses for a few seconds.
Although these will help you determine what is causing the S.E.S. light
to come on, not all diagnostics are that simple. This is ment to be a guide
to point you towards what the problem might be. Dont be suprized if there
are other causes of the problem with equipment other than the main
components listed below.
When you done,
DON'T FORGET TO REMOVE THE PAPER CLIP FROM THE ALDL
CONNECTOR BEFORE STARTING THE VEHICLE.
Here are some codes that you can use to get you started.
12 Diagnostic Mode
13 Oxygen sensor or circuit
14 Coolant sensor or circuit / high temperature indicated
15 Coolant sensor or circuit / low temperature indicated
16 Transmission speed error (4L60 or 4.3L "S" & "T" series w/ manual)
17 Crank signal circuit shorted or faulty ECM
18 Crank signal circuit open or faulty ECM
19 Fuel pump circuit short
19 Crankshaft position sensor (1988-1991 models)
20 Fuel pump circuit open
21 Throttle Position Sensor (TPS) circuit or plunger
22 Throttle Position Sensor (TPS) out of adjustment
21/22 Grounded wide-open-throttle (WOT) circuit at same time
23 Manifold Absolute Temperature (MAT) sensor or circuit / low temp.
24 Vehicle Speed Sensor (VSS) or circuit
25 Manifold Air Temperature (MAT) sensor or circuit / high temp.
26 Throttle switch circuit shorted
27 Throttle switch circuit open
31 Turbo over boost (Turbo models)
31 Canister purge solenoid circuit
31 Camshaft sensor or circuit
31 EGR circuit (1988 to 1990 TBI)
31 Shorted MAP sensor circuit
32 BARO sensor or circuit (carbureted models)
32 EGR circuit (fuel-injected models)
32 Open MAP sensor circuit
33 Manifold Absolute Pressure (MAP) sensor or circuit (low vacuum)
33 MAF (Mas Air Flow) sensor or circuit
33 Manifold Absolute Pressure (MAP) sensor signal voltage high
34 Manifold Absolute Pressure (MAP) sensor signal voltage low
34 MAF (Mas Air Flow) sensor or circuit
35 Idle Air Control (IAC) valve or circuit
35 Idle Speed Control (ISC) switch or circuit (shorted)
36 Mass Air Flow (MAF) sensor burn-off circuit
36 Closed throttle shift control (1991)
37 MAT sensor temp. high (1984-1986)
37 Brake switch stuck on (4L60-E transmission)
38 Brake Input Circuit (brake light switch)
38 MAT sensor temp. low (1984-1986)
38 Brake switch stuck off (4L60-E transmission)
39 Torque converter clutch
39 Knock sensor circuit shorted (4.3L, manual trans., "S" & "T" pick-up)
40 Power steering pressure switch circuit
41 No distributor signals to ECM, or faulty ignition module
41 Cylinder select error
42 Electronic Spark Timing (EST) circuit
43 Throttle Position Sensor (TPS) out of adjustment
43 Knock sensor signal
44 Oxygen sensor or circuit - lean exhaust
45 Oxygen sensor or circuit - rich exhaust
46 Power steering pressure switch (4 cylinder - air-conditioned modules)
46 Vehicle Anti-Theft System (VATS)
47 Air conditioning clutch and cruise circuit
48 Misfire diagnosis
53 System over-voltage (ECM over 17.7 volts)
53 EGR system (carbureted models)
53 Alternator voltage out of range
55 ECM/PCM error
55 Oxygen sensor circuit or ECM
56 Vacuum sensor circuit
58 PASS key fuel enable circuit
58 Transmission code - TTS high temp. (sensor or signal wire grounded)
59 Transmission code - TTS low temp. (sensor or signal wire open)
61 Oxygen sensor signal faulty
63 MAP sensor voltage high
64 MAP sensor voltage low
64 Right side oxygen sensor lean (dual sensor models)
65 Right side oxygen sensor rich (dual sensor models)
66 Air conditioning pressure sensor circuit
67 Air conditioning pressure sensor or clutch circuit (Chevrolet)
67 Cruise switch circuit
68 Air conditioning relay circuit (Chevrolet)
68 Cruise system problem
69 Air conditioning clutch circuit (Chevrolet)
69 Air conditioning head pressure switch circuit
69 Transmission code - Torque converter stuck on (4L60-E)
72 Gear selector switch (Chevrolet)
72 Transmission code - Vehicle Speed Sensor (VSS) signal loss (4L60-E)
75 System voltage low (charging system problem)
79 Transmission fluid temperature high (4L60-E)
81 Transmission code - QDM solenoid "A" (1st and 2nd gear) current error
82 Transmission code - QDM solenoid "B" (2nd and 3rd gear) current error
99 Power management, cruise control system
DON'T FORGET TO REMOVE THE PAPER CLIP FROM THE ALDL
CONNECTOR BEFORE STARTING THE VEHICLE.
http://www.troublecodes.net/articles/AT/palm/service_engine_soon_light_on.JPG
WTF?!?!?
So your driving down the road minding your own business, you happen to look
at your instrument panel and to your suprize the "Service Engine Soon" has
appeared out of no where. If your truck is pre '95 year model, it is most likely
equiped with On Board Diagnostics 1 (OBD1). Instead of going to a Dealer
and/or paying out the ying-yang for a professional to do it with an expensive
scanner, check out your stationary supplies first.
http://img115.exs.cx/img115/7869/tn_PaperClip.jpg
This aint no super-duper code scanner, but when used correctly it works and
gives you the same results.
http://www.vanforum.net/Extern/Technik/Images/Bilder/Connector-1.jpg.
This is an illistration of your Assembly Line Diagnostic Lead (ALDL) Connector.
You might have seen this right near the bottem center of you dash, or under
it around the steering wheel area. Locate this on your vehicle then we could
begin checking the codes.
The above is for most GM vehicles 1981-1995. Starting in 1994 the OBD2
system and connector were phased in with full implementation in 1996 (the
above connector is OBD1).
Once you've found your ALDL connector your going to need to bend that
paper clip in to a "U" like shape. With the ignitionoff,
insert the paper clip into terminal "A" & "B" to jump them. Get a pen &
a piece of paper or something to right on, cause you might need it.
Next, Turn your ignition into the ON postion (just before it would normally
start), DO NOT START!
At this point with your undivided attention observe the S.E.S. light on the
dash board, it will begin to blink number codes in a morse code fashion.
EX.
http://www.s10planet.com/gallery/uploads/51/SESsmall.JPG (Pause) http://www.s10planet.com/gallery/uploads/51/SESsmall.JPG http://www.s10planet.com/gallery/uploads/51/SESsmall.JPG
......Blink..........................Blink........ .Blink
.....(One)................................(Two) = 12
As you can see it's not that hard to figure out...
That flashing sequence is Code # 12
Each code will flash its sequence 3 times before moving to the next code.
When checking checking them, Code 12 will always come up first to
let you know its in diagnotic mode. This will also be the last code you
see which indicates there are no others after it(and it will start over).
Even if your SES light doesn't stay on, each code is stored in memory
for a number(50 ?) of ignition cycles each time the fault is detected.
So you can go back and check even if the light went out by itself.
If you repair the problem the codes can be cleared by disconnecting
the battery, or pulling the ECM fuses for a few seconds.
Although these will help you determine what is causing the S.E.S. light
to come on, not all diagnostics are that simple. This is ment to be a guide
to point you towards what the problem might be. Dont be suprized if there
are other causes of the problem with equipment other than the main
components listed below.
When you done,
DON'T FORGET TO REMOVE THE PAPER CLIP FROM THE ALDL
CONNECTOR BEFORE STARTING THE VEHICLE.
Here are some codes that you can use to get you started.
12 Diagnostic Mode
13 Oxygen sensor or circuit
14 Coolant sensor or circuit / high temperature indicated
15 Coolant sensor or circuit / low temperature indicated
16 Transmission speed error (4L60 or 4.3L "S" & "T" series w/ manual)
17 Crank signal circuit shorted or faulty ECM
18 Crank signal circuit open or faulty ECM
19 Fuel pump circuit short
19 Crankshaft position sensor (1988-1991 models)
20 Fuel pump circuit open
21 Throttle Position Sensor (TPS) circuit or plunger
22 Throttle Position Sensor (TPS) out of adjustment
21/22 Grounded wide-open-throttle (WOT) circuit at same time
23 Manifold Absolute Temperature (MAT) sensor or circuit / low temp.
24 Vehicle Speed Sensor (VSS) or circuit
25 Manifold Air Temperature (MAT) sensor or circuit / high temp.
26 Throttle switch circuit shorted
27 Throttle switch circuit open
31 Turbo over boost (Turbo models)
31 Canister purge solenoid circuit
31 Camshaft sensor or circuit
31 EGR circuit (1988 to 1990 TBI)
31 Shorted MAP sensor circuit
32 BARO sensor or circuit (carbureted models)
32 EGR circuit (fuel-injected models)
32 Open MAP sensor circuit
33 Manifold Absolute Pressure (MAP) sensor or circuit (low vacuum)
33 MAF (Mas Air Flow) sensor or circuit
33 Manifold Absolute Pressure (MAP) sensor signal voltage high
34 Manifold Absolute Pressure (MAP) sensor signal voltage low
34 MAF (Mas Air Flow) sensor or circuit
35 Idle Air Control (IAC) valve or circuit
35 Idle Speed Control (ISC) switch or circuit (shorted)
36 Mass Air Flow (MAF) sensor burn-off circuit
36 Closed throttle shift control (1991)
37 MAT sensor temp. high (1984-1986)
37 Brake switch stuck on (4L60-E transmission)
38 Brake Input Circuit (brake light switch)
38 MAT sensor temp. low (1984-1986)
38 Brake switch stuck off (4L60-E transmission)
39 Torque converter clutch
39 Knock sensor circuit shorted (4.3L, manual trans., "S" & "T" pick-up)
40 Power steering pressure switch circuit
41 No distributor signals to ECM, or faulty ignition module
41 Cylinder select error
42 Electronic Spark Timing (EST) circuit
43 Throttle Position Sensor (TPS) out of adjustment
43 Knock sensor signal
44 Oxygen sensor or circuit - lean exhaust
45 Oxygen sensor or circuit - rich exhaust
46 Power steering pressure switch (4 cylinder - air-conditioned modules)
46 Vehicle Anti-Theft System (VATS)
47 Air conditioning clutch and cruise circuit
48 Misfire diagnosis
53 System over-voltage (ECM over 17.7 volts)
53 EGR system (carbureted models)
53 Alternator voltage out of range
55 ECM/PCM error
55 Oxygen sensor circuit or ECM
56 Vacuum sensor circuit
58 PASS key fuel enable circuit
58 Transmission code - TTS high temp. (sensor or signal wire grounded)
59 Transmission code - TTS low temp. (sensor or signal wire open)
61 Oxygen sensor signal faulty
63 MAP sensor voltage high
64 MAP sensor voltage low
64 Right side oxygen sensor lean (dual sensor models)
65 Right side oxygen sensor rich (dual sensor models)
66 Air conditioning pressure sensor circuit
67 Air conditioning pressure sensor or clutch circuit (Chevrolet)
67 Cruise switch circuit
68 Air conditioning relay circuit (Chevrolet)
68 Cruise system problem
69 Air conditioning clutch circuit (Chevrolet)
69 Air conditioning head pressure switch circuit
69 Transmission code - Torque converter stuck on (4L60-E)
72 Gear selector switch (Chevrolet)
72 Transmission code - Vehicle Speed Sensor (VSS) signal loss (4L60-E)
75 System voltage low (charging system problem)
79 Transmission fluid temperature high (4L60-E)
81 Transmission code - QDM solenoid "A" (1st and 2nd gear) current error
82 Transmission code - QDM solenoid "B" (2nd and 3rd gear) current error
99 Power management, cruise control system
DON'T FORGET TO REMOVE THE PAPER CLIP FROM THE ALDL
CONNECTOR BEFORE STARTING THE VEHICLE.