You Can Do It!
GM
ii
Plug It In
•
Test connector usually found
under the left side of the
dashboard.
•
Set Selector switch to
ECM A-B
position.
•
Make sure ignition is off. Plug
Code Reader into test connector.
Read Fault Codes
•
Turn on ignition.
DO NOT
START ENGINE.
•
Read codes from flashing
"Check Engine" or "Service
Engine Soon" light.
Pinpoint Problems
•
Locate fault code(s) in the
appropriate Service Codes List.
1
CHECK ENGINE
CHECK ENGINE
SERVICE
SERVICE
ENGINE
ENGINE
SOON
SOON
2
3
triev
CODE DEFINITION
haft or Crankshaft sensor - cir
el Injector circuit is not working p
possible blown fuel injector fuse
Ignition system fault - Intermittent 7X sign
loss of 58X signal or 6X signal (Saturn)
1
Throttle position sensor (TPS) - signal voltag
high during engine idle or deceleration
22
Throttle position sensor (TPS) - signal
low during engine idle
Fuel cutoff relay circuit - open
ground
23
Manifold air temperature (M
voltage is low or high
Throttle position senso
Mixture Control (M
circuit problems
Intake Air T
Vehicle sp
problem
Ma
Read manual for a complete description of the Code Reader and
it's proper use and operation.
Summary of Contents for GM 3123
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