Kohler LH630-775 Service Manual page 47

Mounted on the throttle body/intake manifold and
operated directly off the end of the throttle shaft, the
TPS works like a rheostat, varying the voltage signal
to the ECU in direct correlation to the angle of the
throttle plate. This signal, along with the other sensor
signals, is processed by the ECU and compared to the
internal pre-programmed maps to determine the
required fuel and ignition settings for the amount of
load.
The correct position of the TPS is established and set
at the factory. Do not loosen the TPS or alter the
mounting position unless absolutely required by fault
code diagnosis or throttle shaft service. If the TPS is
loosened or repositioned the "TPS Initialization
Procedure" (see pages 5B.7 and 5B.8) must be
performed to re-establish the baseline relationship
between the ECU and the TPS.
Service
The TPS is a sealed, non-serviceable assembly. If
diagnosis indicates a bad sensor, complete
replacement is necessary. If a blink code indicates a
problem with the TPS, it can be tested as follows.
1. Counting the number of turns, back out the idle
speed adjusting screw (counterclockwise) until
the throttle plate can be closed completely.
2. Disconnect the main harness connector from the
ECU, but leave the TPS mounted to the throttle
body/manifold.
3. Connect the ohmmeter leads as follows:
(See chart on page 5B.24.) Connect the Red
(positive) ohmmeter lead to #8 pin terminal, and
the Black (negative) ohmmeter lead to #4 pin
terminal. Hold the throttle closed and check the
resistance. It should be 800-1200 Ω Ω Ω Ω Ω .
4. Leave the leads connected to the pin terminals as
described in step 3. Rotate the throttle shaft
slowly counterclockwise to the full throttle
position. Monitor the dial during rotation for
indication of any momentary short or open
circuits. Note the resistance at the full throttle
position. It should be 1800-3000 Ω Ω Ω Ω Ω .
5. Disconnect the main wiring harness connector
from the TPS, leaving the TPS assembled to the
manifold. Refer to the following chart and
perform the resistance checks indicated between
the terminals in the TPS socket, with the throttle
in the positions specified.
Throttle
Between
Position
Terminals
2 & 3
Closed
1 & 3
Closed
2 & 3
Full
1 & 3
Full
1 & 2
Any
If the resistance values in steps 3, 4, and 5 are
within specifications, go to step 6.
If the resistance values are not within
specifications, or a momentary short or open
circuit was detected during rotation (step 4), the
TPS needs to be replaced, go to step 7.
6. Check the TPS circuits (input, ground) between
the TPS plug and the main harness connector for
continuity, damage, etc., Pin Circuits #8 and #4.
See chart on page 5B.24.
a. Repair or replace as required.
b. Turn the idle speed screw back in to its
original setting.
c. Reconnect connector plugs, start engine and
retest system operation.
7. Remove the two mounting screws from the TPS.
Save the screws for reuse. Remove and discard
the faulty TPS. Install the replacement TPS and
secure with the original mounting screws.
a. Reconnect both connector plugs.
b. Perform the "TPS Initialization Procedure"
integrating the new sensor to the ECU.
TPS Initialization Procedure
"32 Pin" (MSE 1.1) Plastic-Cased ECU (Auto-Learn
Initialization)
1. Check that the basic engine, all sensors, fuel, fuel
pressure, and battery are good and functionally
within specifications.
Important!
2. Remove/disconnect ALL external loads from the
engine (belts, pumps, electric PTO clutch,
alternator, rectifier-regulator, etc.).
Section 5B
EFI Fuel System
Resistance
Continuity
Value (Ω)
800-1200 Yes
1800-3000 Yes
1800-3000 Yes
800-1200 Yes
1600-2500 Yes
5B.7
5B