Question about 1988 Toyota Supra

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Acceleration hesitaiton, speedometer, overdrive light flashing

I just acquired a 1988 automatic supra turbo. I am fairly new to supra's and very new to and auto turbo. The car is immaculate with 130,000 miles on it. The car runs great, idles great and drives down the road flawlessly. Now the problem...first of all the speedometer does not work and i can hear a gear grind sound behind the speedometer. If there is a quick fix for this?i do not know. Secondly when i accelerate I am getting no power and major hesitation. I can slowly press the pedal down or mash it WOT and the same thing happens. It lags and will not really go above 4000 rpms. I can see the turbo gage working when i accelerate it is going up to about 7 ps and usually stays there as long as i hold the pedal down. The car stutters and feels like it is confused. Shifting differently everytime i press down th pedal. I also noticed while on a neiborhood cruise tongiht the O/D light on the dash started to blink/flash a few this a code?does this have to do with my spedometer?could this maybe all be tied into the acceleration problem?? any advice or help would be greatly appreciated. thanks

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  • wow2acct May 21, 2009

    awesome. thanks for such a quick response. i removed the cluster from the dash and found the square nylon/ plastic cable which goes into the back o f the speedometer stripped. do you have an suggestion where to get or order a replacement for this section of the cable? THANKS AGAIN



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First off, I have a 1987 Supra non-turbo and I have seen a similar problem on my car. Probably one part of the two part speedo cable has broken, or the speed sensor has failed. The speedo cable turns a speed sensor which is part of the speedo gage cluster. The signal right now from the speed sensor to the computer is probably zero so the PCM thinks the car is stopped. The PCM has a limit on how high the engine will rev while the car is not moving. This is also the "limp home mode" max rpm in case the speed sensor fails. So if you fix your speedo/speed sensor, I think the acceleration problem will go away. The cable is in two parts--a "lower cable" which goes from the tranny to a junction and an "upper cable" which goes from the junction to the speedo. You will need to determine which cable is broken or if the speed sensor itself has a broken part.

To check the cable, find the junction under the car on the passengers side and disconnect it. The cable frequently breaks right at this spot. You will be able to turn the upper speedo cable by hand and have a partner listen/look for results on the speedo cluster. If the cable checks out, you may have to pull the instrument cluster to check what is wrong with the speed sensor.

Secondly, the flashing O/D light is signaling you that there is a trouble code waiting (probably for the transmission which also needs a speed signal). You can obtain trouble codes from the PCM via the diagnostic connector in the engine compartment. The connector is on the driver's side of the compartment just behind the fuse box. It is labeled "diagnostics". Using a paper clip or a hair pin and a jumper wire, connect the terminals "T" and "E1". (there is a guide to the terminals on the inside of the plastic flip cover.) Turn the ignition to on but do not start the car. The check engine light will start flashing two digit codes. (Four flashes followed by two flashes=Code 42= speed sensor signal lost.) There will be a pause then the next code. At the end of the codes, it will start repeating the sequence of codes again until you turn off the ignition. If there are no codes, the check engine light will just flash continously once every second. Don't forget to remove the diagnostic jumper before starting or driving the car.

Posted on May 20, 2009

  • David Melrose May 21, 2009

    Call Toyota first and see if the part is listed as separate from the upper cable. It may be part of the upper cable assembly. If it is separate, it might still be available for less money. For used parts, try TAP Recycling in Rancho Cordova, CA.


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The car wont sputter if the cable isnt hooked up, mine drove "flawlessly" when i didnt have it hooked up at all, (cluster completely out) just didnt know how fast i was goin lol, when your timing is off u wont beable to drive very fast

Posted on Jul 27, 2009


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