Mechanics

ERROR CODE AND HOW TO CORRECT IT.

2000 Ford Focus

Computer problem
2000 Ford Focus 4 cyl Front Wheel Drive Automatic 79000 miles

I have an error code as follows. P0121 Throttle/Pedal Position Sensor/Switch A Circuit Range/Performance Problem
What is this telling me and how do I correct the problem? I am an old time mechanic and have not had much dealings with the computer code type of work.
Thanks.
Avatar
Davismotorsports
August 10, 2008.



SELF-DIAGNOSTICS - EEC-V - CNG, FLEX-FUEL & GASOLINE -2000 Ford Focus ...
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NOTE: After each service or repair procedure has been completed, reconnect all components. Clear DTCs and repeat QUICK TEST procedures to ensure all EEC-V systems are working properly and DTCs are no longer present.

TEST DH: THROTTLE POSITION SENSOR
Diagnostic Aids
Perform this test only when directed by QUICK TEST. This test is intended to diagnose the following.
 TP Sensor
 Wiring Harness Circuits (PWR GND, SIG RTN, TP, VPWR & VREF)
 Powertrain Control Module (PCM)
Normal range of throttle angle measurement for TP sensor is 0-96.6 degrees. To pass QUICK TEST procedure, range of throttle rotation (in degrees) must be within 3 percent of specification. To prevent replacement of good components, be aware the following non-EEC related areas may be at fault:
 Idle Speed
 Binding Throttle Shaft Or Linkage
 TP Sensor Not Seated
1) KOEO/KOER DTC P1124: Check For Other DTCs

DTC P1124 indicates TP sensor rotational setting may be out of self-test range. Possible causes for this fault are:
 Faulty TP Sensor
 Faulty Powertrain Control Module (PCM)
Perform KOEO ON-DEMAND SELF-TEST and KOER ON-DEMAND SELF-TEST . Check for DTC P1400. If DTC P1400 is also present, go to TEST HE. If DTC P1400 is not also present with DTC P1124, go to next step.
2) Check For Binding Throttle Plate

Inspect throttle body for binding. If throttle body is binding, check for binding throttle or cruise control linkage, vacuum line or harness interference. Repair as necessary. If no mechanical problem is found, go to step 8).
3) DTC P1120: Check For Frayed Wires Or Corrosion On Connector Terminals
DTC P1120 indicates TP sensor closed throttle position is below range of 3.4 percent (.17 volt) Possible causes for this fault are:
 Damaged Wiring Harness Or Connectors
 Open In VREF Circuit.
 Faulty TP Sensor

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 Faulty Powertrain Control Module (PCM)
Inspect TP sensor connector for loose, damaged or corroded terminals. Inspect wiring harness between TP sensor and PCM for damage or corrosion. Repair as necessary. If no problem is found, go to next step.
4) Check For Stuck TP Sensor

Turn ignition switch to OFF position. Using scan tool, select TP V PID from PID/DATA MONITOR & RECORD menu. While observing TP V PID, slowly move throttle through range from closed to wide open throttle. If PID value indicates any sudden drop to less than 9.85 percent (.49 volt), go to next step. If PID value increases and decreased gradually and smooth, go to step 20).
5) Check VREF Circuit Voltage

Disconnect TP sensor connector. Turn ignition switch to ON position. Measure voltage between VREF and SIG RTN terminals at TP sensor harness connector. See Fig. 53-Fig. 56 . If voltage is 4-6 volts, go to next step. If voltage is not 4-6 volts, reconnect sensor and go to TEST C.
Fig. 53: Identifying TP Sensor Circuits & Connector Terminals (Contour 2.0L, Cougar
2.0L, Escort 2.0L & Mystique 2.0L) Courtesy of FORD MOTOR CO.
Fig. 54: Identifying TP Sensor Circuits & Connector Terminals (Focus)
Courtesy of FORD MOTOR CO.
Fig. 55: Identifying TP Sensor Circuits & Connector Terminals (LS)
Courtesy of FORD MOTOR CO.
Fig. 56: Identifying TP Sensor Circuits & Connector Terminals (Except Contour 2.0L, Cougar 2.0L, Escort 2.0L, Focus, LS & Mystique 2.0L)
Courtesy of FORD MOTOR CO.
6) Check TP Circuit Resistance
Turn ignition switch to OFF position. Disconnect PCM connector(s). Inspect connector for loose, damaged or corroded terminals and repair as necessary. Measure resistance between PCM connector terminal C57 (TP) on LS or terminal No. 89 (TP) on all other models and TP terminal at TP sensor harness connector. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in TP circuit.
7) Check TP Sensor Signal To PCM
Reconnect PCM harness connector(s). Start engine and idle for 2 minutes. Using scan tool, select TP V PID from PID/DATA MONITOR & RECORD menu. While observing TP V PID, slowly open throttle. If at any time TP V PID voltage falls between 3.42-9.85 percent (.17-.49 volt), replace TP sensor. If voltage does not fall between 3.42-9.85 percent (.17-.49 volt), repeat QUICK TEST. If DTC P1120 is still present, go to step 20).

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8) DTC P0123 Or P0124

These DTCs indicate TP signal is more than self-test maximum. Possible causes for this fault are:
 TP Sensor Not Seated Correctly
 Faulty TP Sensor
 TP Circuit Shorted To VREF Or VPWR
 VREF Circuit Shorted To VPWR
 Open In SIG RTN Circuit
 Faulty PCM
Turn ignition switch to OFF position. Disconnect TP sensor connector. Inspect connector for loose, damaged or corroded terminals and repair as necessary. Turn ignition switch to ON position. Using scan tool, select TP V PID from PID/DATA MONITOR & RECORD menu. If TP V PID voltage is 3.42 percent (.17 volt) or more, go to step 10). If TP V PID voltage is less than 3.42 percent (.17 volt), go to next step.
9) Check VREF Circuit Voltage

Measure voltage between VREF and SIG RTN terminals at TP sensor harness connector. If voltage is 4-6 volts, replace TP sensor. If voltage is not 4-6 volts, reconnect components and go to TEST C.
10) Check TP Circuit For Short To Power
Turn ignition switch to OFF position. Leave TP sensor disconnected. Disconnect PCM connector (s). Inspect connector for loose, damaged or corroded terminals and repair as necessary. Using a DVOM, measure resistance between PCM harness connector TP terminal and both VPWR and VREF terminals. Both VREF terminals on 150-pin PCM models. If any resistance measurement is 10 k/ohms or less, repair short in affected circuit. If all resistance measurements are more than 10 k/ohms, replace PCM. See appropriate REMOVAL, OVERHAUL & INSTALLATION article. Program PCM. See FLASH VEHICLE IDENTIFICATION BLOCK PROCEDURE.
11) DTC P0122
This DTC indicates TP signal is less than self-test minimum of .17 volt. Possible causes for this fault are:
 TP Sensor Not Seated Correctly
 Faulty TP Sensor
 Open TP Or VREF Circuit
 TP Circuit Shorted To SIG RTN Or PWR GND
 Faulty PCM
NOTE: An intermittent fault can cause a Continuous Memory DTC P0122. If a Continuous Memory DTC P0122 is still present after performing steps 11)-14) , go to step 20).
Turn ignition switch to OFF position. Disconnect TP sensor connector. Inspect connector for

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loose, damaged or corroded terminals and repair as necessary. Connect a jumper wire between VREF and TP terminals at TP harness connector. Turn ignition switch to ON position.
NOTE: If communication link error is displayed, remove jumper wire and go to step 14).
Using scan tool, select TP V PID from PID/DATA MONITOR & RECORD menu. If TP V PID voltage is more than 9.3 percent (4.65 volts), replace TP sensor. If PID voltage is 9.3 percent (4.65 volts) or less, remove jumper wire and go to next step.
12) Check VREF Circuit Voltage

Turn ignition switch to ON position. Measure voltage between VREF and SIG RTN terminals at TP sensor harness connector. If voltage is 4-6 volts, go to next step. If voltage is not 4-6 volts, reconnect sensor and go to TEST C.
13) Check TP Circuit Resistance
Turn ignition switch to OFF position. Leave TP sensor disconnected. Disconnect PCM connector (s). Inspect connector for loose, damaged or corroded terminals and repair as necessary. Measure resistance between PCM connector terminal C57 (TP) on LS or terminal No. 89 (TP) on all other models and TP terminal at TP sensor harness connector. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in TP circuit.
14) Check TP Circuit For Short To SIG RTN Or PWR GND

Disconnect scan tool from Data Link Connector (DLC). Using a DVOM, measure resistance between PCM harness connector TP terminal and both SIG RTN and PWR GND terminals. If either resistance measurement is 10 k/ohms or less, repair short in affected circuit. If both resistance measurements are more than 10 k/ohms, replace PCM. See appropriate REMOVAL, OVERHAUL & INSTALLATION article. Program PCM. See FLASH VEHICLE IDENTIFICATION BLOCK PROCEDURE.
15) Continuous Memory DTC P1121

This DTC indicates TP signal is inconsistent with MAF sensor signal. Possible causes for this fault are:
 TP Sensor Not Seated Correctly
 Faulty TP Sensor
 Air Leak Between MAF Sensor & Throttle Body
Attempt to start engine. If engine will start, go to next step. If engine will not start, check for cracks or openings in air induction system between MAF sensor and throttle body. If air induction system is okay, go to TEST A.
16) Check Operation Of TP Sensor

Turn ignition switch to OFF position. Connect scan tool to Data Link Connector (DLC). Turn ignition switch to ON position. Using scan tool, select TP V PID from PID/DATA MONITOR &

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RECORD menu. While observing TP V PID voltage, slowly move throttle through range from closed position to wide open throttle. If TP V PID voltage changes from 9.85-93.00 percent (.49-4.65 volts), go to next step. If TP V PID voltage does not change from 9.85-93.00 percent (.49-4.65 volts), replace TP sensor. Repeat QUICK TEST to verify repair.
17) Check Operation Of TP Sensor While Driving Vehicle

Drive vehicle (vary throttle position) while selecting TP V PID and LOAD PID from PID/DATA MONITOR & RECORD menu. If TP V PID voltage is 49.02 percent (2.44 volts) or less and LOAD PID value is 30 percent or more, go to next step. If TP V PID voltage is more than 49.02 percent (2.44 volts) and LOAD PID value is less than 30 percent, check for cracks or openings in air induction system between MAF sensor and throttle body. For air restrictions, go to TEST HU. If air induction system is okay, replace TP sensor.
18) Check TP Sensor Low With Engine Under Load

Start engine and allow to idle. If engine does not start, go to TEST A. Drive vehicle (vary throttle position) in higher gears (preferably Overdrive) while selecting TP V PID and LOAD PID from PID/DATA MONITOR & RECORD menu. If TP V PID is 4.82% (.24 volt) or more and LOAD PID is 55% or less, fault is intermittent and cannot be duplicated at this time. Testing is complete. If TP V PID is less than 4.82% (.24 volt) and LOAD PID is more than 55%, tighten TP sensor (if necessary). Clear DTCs. Perform test drive utilizing all phases of vehicle operation. Perform QUICK TEST. If DTC Continuous Memory P1121 is still present, replace MAF sensor.
NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 18) to step 20). No test procedures have been omitted.
20) Continuous Memory DTC P1120 Or P1125

These DTCs indicate TP signal went to less than .49 volt or more than 4.65 volts sometime during the last 80 drive cycles. Possible causes for this fault are:
 Faulty TP Sensor Wiring Harness Or Connector
 Faulty TP Sensor
With scan tool connected, start engine and allow to idle. Raise engine speed to 1500 RPM for 5 seconds and return to idle. Using scan tool, select TP V PID from PID/DATA MONITOR & RECORD menu. While observing PID, lightly tap on TP sensor to simulate road shock. Wiggle sensor connector and wiring harness. If TP PID voltage stays within normal operating range (.49-4.65 volts), go to next step. If TP PID voltage goes out of range, inspect TP sensor installation. Repair as necessary and retest. If TP sensor installation is okay, replace TP sensor.
21) Check Wiring Harness Between TP Sensor & PCM
Turn ignition switch to OFF position. Disconnect PCM connector(s). Inspect connector for loose, damaged or corroded terminals and repair as necessary. Reconnect PCM connector. Using scan tool, select TP V PID from PID/DATA MONITOR & RECORD menu. While observing PID, wiggle small sections of wiring harness starting at the TP sensor working toward PCM. If PID voltage stays within normal operating range (.49-4.65 volts), problem is intermittent and cannot be identified at this time. Go to TEST Z. If PID voltage goes out of range, isolate fault and repair

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as necessary.
22) KOER & Continuous Memory DTC P0121: Verify KOER On-Demand Self-Test Completion

Start engine and allow to idle. Using scan tool, enter KOER ON-DEMAND SELF-TEST. Attempt to drive vehicle while still in KOER on-demand self-test. If KOER on-demand self-test terminates when placing gear selector lever into Drive or Reverse, go immediately to step 25). If KOER on-demand self-test does not terminate, turn ignition switch to OFF position and wait 15 seconds. Start engine again. Repeat KOER ON-DEMAND SELF-TEST. If DTC P0121 is still present or KOER ON-DEMAND SELF-TEST does not terminate, go to next step. If KOER ON-DEMAND SELF-TEST terminates and DTC P0121 is not present, problem is intermittent and cannot be identified at this time.
CAUTION:DO NOT clean throttle bore or plate area. Cleaning will damage throttle body assembly.
23) Isolate Binding Or Sticking Problem Disconnect accelerator and speed control cables from throttle body linkage. Rotate linkage on throttle body. If sticking, binding or grabbing is felt when rotating throttle body linkage, replace throttle body assembly. If throttle body linkage rotates freely without sticking, binding or grabbing, replace faulty cable(s). Repeat QUICK TEST. If DTC P0121 is still present, go to next step.
24) Check TP Sensor Mechanical Operation

Turn ignition switch to ON position. Using scan tool, select TP V PID from PID/DATA MONITOR & RECORD menu. While observing TP V PID voltage, slowly move throttle through range from closed position to wide open throttle. If TP V PID voltage increases smoothly during throttle movement, problem cannot be identified at this time. If TP V PID voltage does not increase smoothly during throttle movement, turn ignition switch to OFF position and replace TP sensor.
25) Check TP & SIG RTN Circuit For Opens

Turn ignition switch to OFF position. Disconnect PCM connector(s) and TP sensor connector. Measure resistance of TP circuit between PCM harness connector terminal and TP sensor harness connector terminal. See Fig. 53-Fig. 56 . Measure resistance of SIG RTN circuit between PCM harness connector terminal and TP sensor harness connector terminal. If each resistance measurement is less than .5 ohm, replace TP sensor. Repeat QUICK TEST to verify repair. If either resistance measurement is .5 ohm or more, repair open in affected circuit. Repeat QUICK TEST to verify repair.

8/10/2008


http://www.2carpros.com/forum/automotive_pictures/62217_TPS_1.jpg


Merlin2021
Aug 10, 2008.