Your Vehicle: 2001 Ford Escort ZX2 L4-2.0L DOHC VIN 3
 
Vehicle » Powertrain Management » Computers and Control Systems » Testing and Inspection » Pinpoint Tests » TH: Reverse Switch (RS) - Pinpoint Test  
 
 
  TH: Reverse Switch (RS) - Pinpoint Test  
 

TH: Reverse Switch (RS)

TH: Introduction See: TH: Reverse Switch (RS) - Introduction

TH1 DTC P0812: CHECK RS SWITCH FUNCTION

Note: During KOEO Self-Test, gearshift lever in NEUTRAL.

  • Key on, engine off.
  • Access RS PID and observe PID cycling ON/OFF with gear shift lever in and out of REVERSE.

Does reading change from ON to OFF?
Yes

  • KEY OFF. Fault intermittent DISCONNECT PCM. INSPECT both ends of the

connector for damaged or pushed out pins, corrosion, loose wires. REPAIR
as necessary. If OK, REPLACE PCM (refer to Section 2, Flash Electrically Erasable Programmable Read Only Memory (EEPROM) See: Programming and Relearning\Flash Electrically Eraseable Programmable Read Only Memory - Flash EEPROM
).

No

  • KEY OFF. GO to TH2

.

TH2 CHECK RS SWITCH RESISTANCE

  • Locate the reverse switch (RS) near the transmission shift linkage.
  • Inspect switch and bracket for damage, bent or broken conditions. Repair as required.
  • Disconnect RS harness connector.
  • Measure the resistance between the reverse switch terminals with the shift lever in reverse.

Is the resistance less than 5.0 ohms?
Yes

  • GO to TH3

.

No

  • REPLACE the RS switch.

TH3 CHECK RS CIRCUIT FOR OPEN IN HARNESS

  • Disconnect scan tool.
  • Disconnect PCM.
  • Measure resistance of the RS circuit between PCM harness connector pin and RS harness connector.
  • Where applicable, measure resistance of the SIG RTN circuit between PCM harness connector pin and RS harness connector.

Are both resistances less than 5.0 ohms?
Yes

  • GO to TH4

.

No

  • REPAIR open circuit.

TH4 CHECK RS CIRCUIT FOR SHORT TO SIG RTN OR CHASSIS GROUND IN HARNESS

  • Measure resistance between RS and SIG RTN circuits at the PCM harness connector.
  • Measure resistance between RS circuit at the PCM harness connector and chassis ground.

Are both resistances greater than 10,000 ohms?
Yes

No

  • REPAIR short circuit.