Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSTOYOTA2004CELICA GT, STANDARDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 136 (WIPER/WASHER SYSTEMS)SYSTEM TESTSTEST A: RAIN DROP SENSING FUNCTION DOES NOT OPERATE
2004 Toyota Celica GT, Standard
Test A: Rain Drop Sensing Function Does Not Operate
2004 Toyota Celica GT, StandardSECTION Test A: Rain Drop Sensing Function Does Not Operate
WARNING: This page is about a different car, the 2003 Lexus ES 300 and 2002 Lexus ES 300. However, it is still accessible from the selected car via links, so may be relevant.
NOTE:
For circuit diagram, see Fig 1.
- Check the continuity between the windshield wiper switch assembly terminals. See INSPECTING WIPER SWITCH CONTINUITY table. If continuity is as specified, go to the next step. If continuity is not as specified, replace the windshield wiper switch assembly. See WINDSHIELD WIPER SWITCH ASSEMBLY under REMOVAL & INSTALLATION.INSPECTING WIPER SWITCH CONTINUITY
Switch Operation Tester Connection Specified Condition OFF 4 (AUTO) - 14 (E) No Continuity AUTO 4 (AUTO) - 14 (E) Continuity - Check the continuity between terminals of the windshield wiper switch and windshield wiper relay assembly. See INSPECTING WIPER SWITCH & WIPER RELAY CONTINUITY table. If continuity is as specified, go to the next step. If continuity is not as specified, repair or replace the harness and connector as necessary.INSPECTING WIPER SWITCH & WIPER RELAY CONTINUITY
Item Tester Connection Specified Condition Wiper Switch Assembly - Wiper Relay 15 (VR1) - 8 (VR1) Continuity Wiper Switch Assembly - Wiper Relay 3 (VR2) - 18 (VR2) Continuity Wiper Switch Assembly - Wiper Relay 14 (E) - 19 (CO) Continuity Wiper Switch Assembly - Wiper Relay 4 (AUTO) - 9 (C1) Continuity - Check the continuity between terminals of the windshield wiper relay and the rain sensor. See INSPECTING WIPER RELAY & RAIN SENSOR CONTINUITY table. If continuity is as specified, go to the next step. If continuity is not as specified, repair or replace the harness and connector as necessary.INSPECTING WIPER RELAY & RAIN SENSOR CONTINUITY
Item Tester Connection Specified Condition Wiper Relay - Rain Sensor 16 (SPD) - 3 (WIP) Continuity Wiper Relay - Rain Sensor 6 (SIG) - 1 (SIG) Continuity Wiper Relay - Rain Sensor 17 (PA1) - 2 (AUTO) Continuity - Disconnect the rain sensor. Measure the voltage between terminal No. 1 (SIG) and body ground. If the voltage is 8 volts, go to the next step. If the voltage is not 8 volts, replace the windshield wiper relay assembly.
- Check the continuity between rain sensor terminal No. 4 (ES) and body ground. If continuity exists, go to the next step. If continuity does not exist, repair or replace the harness and connector as necessary.
- Using a oscilloscope, check that the signal waveform appears between terminal No. 3 (WIP) and body ground. See Fig 2. If waveform is as shown in illustration, go to the next step. If waveform is not as shown in illustration, replace the windshield wiper relay assembly.
- Check the voltage between rain sensor terminal No. 2 (AUTO) and body ground follows the standard value as shown. See INSPECTING RAIN SENSOR VOLTAGE table. If the voltage is as specified, replace the windshield wiper relay assembly. If the voltage is not as specified, replace the rain sensor. See RAIN SENSOR under REMOVAL & INSTALLATION.INSPECTING RAIN SENSOR VOLTAGE
Rain Drop Amount Volts Nothing 6.8 A Little (Wiper Switch In LO) 4.1 A Lot (Wiper Switch In HI) 1.3
RENDER: 1.0x
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.