1987 Supra turbo - CRUISE CONTROL failure..... need real help with this one

[suprasvoboda]

hello

i have a 87 turbo that has 90K miles on it... and is a Fabulous car. I rebuilt the engine with a Jaspar motor, rebuild the trubo... everytihg .

the problem is the damn CRUSIE CONTROL has failed. and i cant seemt to find out the problem . I even have a service shop repair manual &( and elelctrical diagram manual )the service techs use even!!

with the servcie manual . it describes how to perform a self diagnosit test u can perform my pressing the set/ accel buttom 3 times in 5 secs, and another test to read the number of flashes in the master switch. Ive done that and the codes are all normal for the switch dianostic. the only one that didnt work was when is was driven 20 it was suppose to keep blinking under and stop blinkin when it was over... that was the only thing that i could find that wasnt to spec in the service manual .

Then is tested the voltage and ohms from the crusie control computer wire harnes (disconnect of course) according to the service manyal ........ that checked out ok.

I replaced the vacumn actuator with 2 other used ones ,.. that didtn work.

I checked the speed control in the instrument cluster .. it was working

I checked the ohm values on the actuator .. it was within spec....


I am not a ASTM mechanic , but a mechanical engineer i am .. and pretty resourceful with intution as well. I ve had this car for 24 years... know it inside , outside and INSIDE OUT!!!

WTF is wrong with this crusie control....? Please help with useful and pertinent suggestions ... im open to almost anything at this point !

THANK YOU TO ALLU MEMBERS !!

 

[3p141592654]

Not sure about 88, but on a 90 you can only use the "press set 3 times" (type B) diagnostics if there was a problem that occurred during use of the cc. Those codes are lost as soon as the cc is turned off, they are not stored. Have you checked for type A codes, especially the speed check?

 

[suprasvoboda]

i checked both type A and B THe B were all fine.. if it blinks quickly once every 1/4 sec its all good

on the type A, the first 3 where all good .. the only one that gave me a non repsonse was when u drive under or over 20 MPH.. there was NO blinking ..... i forget if it was over or under the 20 MPH mark that the manual says.......... i go NO blinks either above or below 20 mph

that was the last code in the TYPE A list.. .and it indicated the "SPEED SENSOR " in teh instrumetn cluster. I check that for continuity 4 times for every revoutino from the input on the speedo cable// it was GOOD .

thats why i am so frustrated........... what esle can it be..? electrical power , vacumn supply ??

 

[3p141592654]

That's what I thought you meant. Did you check the 4 blinks per revolution at the SPD wire going to the cruise control ECU?

My CC failed to operate when my speedo cable got old and the speedometer needle became very jerky. Does your speedometer show a smooth steady speed on the needle when the car is moving?

 

[suprasvoboda]

it jiggles upon start up and about 35 or so it stays steady. WHat does taht have to do with the funcitonality?

 

[suprasvoboda]

please expain your 2nd question ,, about the 4 blinks per rev on the SPD wire going to the CC on ECU....! please

 

[super51fan]

What type of cruise failure. Lights up and turns on and won't set to your speed. Or no power up not working. Toyota systems are usually very good. If it lights up and won't engauge make sure your brake fluid is full . Even if the brake fluid indicator is not on and the fluid is low. The cruise won't engauge.

 

[suprasvoboda]

The main swithc is on, it lights up , and blinks out codes. THere is no brake light on however, and the fluid is almost at the FULL mark.

THE only thing that is not showing a code is TYPE A, when u drive over 20 mph or under. ITs suppose to blink or remain off at that speed, but its never comes on ....

 

[3p141592654]

Check you have speed pulses at the CC ECU SPD input (the pink wire). The failure of the type A speed test above 21mph indicates the ECU is not seeing a good speed signal.

As I said above, if your speedo cable is old and binding, then it won't produce steady pulses and CC will refuse to operate. You need to diagnose the SPD input, that is most likely your problem.

 

[suprasvoboda]

HI

how , exactly do i diagonse the SPD input..?? i think your right , but i need , sepcific iinstructions on how to do this, what conector do i look for;i.e. what number wire is it (Pink i kow) , where is the connector located in the car, should i disconnect it from the computer, or leave it connected while i test it...

THats what im asking ...

thank you so much for your prompt replies and expert knowledge!

 

[3p141592654]

I don't own an 87, so I cannot tell you that. In your first post you said you had the service manual and electrical diagrams. Use those.

In general terms, the CC ECU is under the dash, and the speed wire has I think always been pink. But again, you need to verify for your model year.