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Questions and Answers

Toyota 4Runner O/D Off Light Flashing

Q. Hello Vincent, recently I've been having an intermittent problem with my 1990 Toyota 4Runner 4WD automatic transmission. at times, when I accelerate from 0 mph at a stop light or stop sign the car speeds up very, very slowly. It's as if the car is in second gear not first. The RPMs are around 3,000, which is normal, but the acceleration is eerily slow.

Toyota 4Runner O/D Off Light Flashing

Then once the car reaches about 15 mph it resumes normal acceleration. After this slow acceleration happens for the first time in a particular driving session, the "O/D Off" light blinks on and off. According to the manual, this means that I should contact my toyota dealer as there may be a problem with the transmission.

The light will blink on and off for anywhere from 30 seconds to a few minutes then it will stop on its own. It may or may not begin blinking again some time later in that same driving session. The slow acceleration may occur only once or it may happen a few times before the car returns to normal acceleration. The car's return to normal acceleration and the ending of the blinking of the "O/D Off" light happen at the same time approximately.

Something else to note: when the slow acceleration takes place the car does not begin to roll forward after I release my foot from the brake. Every time, up till now, the car would begin to roll forward, after releasing the brake, since it is an automatic.

I've tried to drive with my local mechanic in the car but we cannot seem to re-create the "slow acceleration" problem when he is there. I hope you can provide me with some information about this situation.

  • 1990 Toyota 4Runner 4WD
  • 3.0 liter V-6
  • Automatic transmission
  • 137,000 miles

Thanks for your time!

A. A self-diagnosis function is built into the electrical control system. Warning is indicated by the overdrive OFF indicator light.

Note: Warning and diagnostic codes can be read only when the overdrive switch is ON. If OFF, the overdrive OFF light is lit continuously and will not blink.

  1. If a malfunction occurs within the speed sensors (No.1 or 2) or solenoids (No.1, 2 or 4), the overdrive OFF light will blink to warn the driver. However, there will be no warning of a malfunction with lock-up solenoid.
  2. The diagnostic code can be read by the number of blinks of the overdrive OFF indicator light when terminals TE1 and E1 are connected.
  3. The throttle position sensor or brake signal are not indicated, but inspection can be made by checking the voltage at terminal TT of the check connector.
  4. The signals to each gear can be checked by measuring the voltage at terminal TT of the check connector while driving.

The diagnostic code (trouble code) is retained in memory by the CPU (of TCCS ECU) and due to back-up voltage, is not canceled out when the engine is turned off. Consequently, after repair, it is necessary to turn the ignition switch off and remove the fuse EFI (15A) or disconnect the TCCS ECU connector to cancel out the diagnostic (trouble) code.

Note: Low battery voltage will cause faulty operation of the diagnosis system. Therefore. always check the battery first. Use a voltmeter and ohmmeter that have an impedance of at least 10K Ohm/Volt.

Check "O/D Off" Indicator Light:

  1. Turn the ignition switch ON.
  2. The "O/D Off" light will come on when the O/D switch is placed at OFF.
  3. When the O/D switch is set to ON, the "O/D Off" light should go out. If the "O/D Off" light flashes when the O/D switch is set to ON, the electronic control system is faulty.

Read Diagnostic Code:

  1. Turn ignition switch and o/d switch to ON. Do not start the engine. Engine NOTE: Warning and diagnostic codes can be read only when the overdrive switch is ON. If OFF, the overdrive OFF light will light continuously and will not blink.
  2. Connect TE1, and E1, terminals of check connector.
  3. Read the diagnostic code as indicated by the number of times the O/D OFF light flashes.

Toyota 4Runner O/D Off Light Flashing

Diagnostic Code Indication:

• If the system is operating normally, the light will flash two times per second.

• In the event of a malfunction, the light will flash 1 time per second. The number of blinks will equal the first number and, after 1.5 seconds pause, the second number of the two digit diagnostic code. If there are two or more codes, there will be a 2.5 seconds pause between each.

NOTE: In the event of several trouble codes occurring simultaneously, indication will begin from the smaller value and continue to the larger.

Toyota 4Runner O/D Off Light Flashing

Toyota 4Runner O/D Off Light Flashing

Additional Information provided courtesy of ALLDATA

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