Briggs & Stratton BIG BLOCK EFI, Repair Manual

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62 Section 2: Troubleshooting DTCs
DTC P0505 Idle Air Control (IAC) Malfunction
Non-Scan Diagnostics
Step Action Yes No
1
1. Disconnect and reconnect IAC and TPS con-
nectors.
2. Turn Ignition ON, Engine OFF.
3. Clear codes.
4. Turn Ignition OFF, and then back ON.
5. Does DTC return?
Go to step 2.
Problem
corrected.
2
1. Start engine and allow it to warm up for 5
minutes.
2. When engine idle speed is stabilized, use
tachometer to record RPM.
3. Is tachometer reading 750-950 RPM?
NOTE: Cold engine temperatures and low battery
voltages can cause high engine idle speeds. For
example, at -18° F. (-28° C.), idle speed can be as
high as 1350 RPM, while low battery voltages at
normal engine operating temperatures can cause
the engine idle speed to reach 1200 RPM.
Look for
intermittent
conditions.
Go to step 3.
3
1. Turn Ignition OFF.
2. Back probe terminal 3 (Pink/Black wire) of
TPS connector.
3. Connect terminal 3 back probe to red meter
test lead on DVOM.
4. Connect black meter test lead on DVOM to a
known good ground.
5. Set DVOM to read volts DC.
6. Start engine and run at idle speed.
7. Does DVOM read 0.5-0.75 volts DC?
Go to step 4.
Reset TPS.
See TPS Removal/
Installation/Adjust-
ment in Section 5.
4
1. Turn Ignition OFF.
2. Remove IAC from throttle body and inspect
for stuck pintel or carbon build up in IAC port.
3. Are either of these conditions found?
Clean or repair as
necessary. Return to
step 2 and repeat test
procedure.
Inspect for intake
tract leaks after the
throttle body.
1
2
3
3
Figure 2-52 TPS Connector.