Questions and Answers

Toyota Celica Has No Cold Fast Idle Q. My fast idle no longer works. This was an intermittent problem for about the last 50,000 miles. It stopped working completely about 5,000 miles ago. I checked the "cold" resistance of the IAC valve and it was within specification. The check engine light is normal.

When I turn on the A/C, it will not force the car to fast idle. When the engine reaches operating temperature, it runs quiet and smooth. My daughter has the same model car with 60,000 miles and hers is starting to have the same problem intermittently.

Other than regular oil changes, filter changes and the spark plugs being replaced at 60,000 miles, nothing has been done to this car. I plan on replacing the timing belt after I fix the fast idle problem. Your help would be appreciated.

• 1999 Toyota Celica Convertible
• Engine Model 5S-FE, 4 Cylinder, 2164 CM
• Manual transmission
• 105,000 miles
• Fuel Injection
• ABS brakes
• P/S, A/C, Cruise control
• Rack and pinion steering

Thank you,
Al

A. At this point I would have to say the Coolant Temperature Sensor (CTS) is likely bad. What you need to do is access the DTCs in the ECM and see what is there. A P0115 would confirm a problem with the CTS circuit.

If the ECM detects the DTC P0115, it operates fail safe function in which the engine coolant temperature is assumed to be 176°F and you will not get a fast cold idle speed.

Added 9/1/00

Vince, Thank you for your help. I was skeptical with your answer because my official Toyota Repair manual says that I will get a check engine light with a P0115 code. My check engine light was normal. I do not have an OBD II tool yet, so I simply removed the connector from the CTS and placed a 2K ohm resistor across the leads. This simulates about 40 degrees Fahrenheit. I started the car and it did not have a fast idle. After the third startup, the computer reset, the fast idle worked perfectly!

Obviously you know more about the Toyota check engine light than they do. I will replace the CTS and hope that it lasts another 100,000 miles.

Thank you again,
AL