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No code 42 intermittent or stored during several times speedo was down. Once do to elbow, twice due to cables. Id read about this before, and had never experienced coded open loop condition. I've had 2 different instrument panels in car during speedo downtime, also.
 

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Discussion Starter #22
No code 42 intermittent or stored during several times speedo was down. Once do to elbow, twice due to cables. Id read about this before, and had never experienced coded open loop condition. I've had 2 different instrument panels in car during speedo downtime, also.
On your stock 85 ecu?
 

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Discussion Starter #24
I can voucher for my 85, as soon as I didn't have a speedometer, I had a hard code MIL (Light stayed on at all times.)
You got lucky I guess.
I went into open loop because of it and my car ran like crap too.

Heh, on a coincidental note, I just picked up TRD83's transmission today. I'm replacing his drive gear's clip. :zzzzz: It took me a freaking sluggish 2.5 hours to get the tranny out. That's super little slow and sad. :crossjerk
 

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Nice Write Up.


Gaskets a good idea.
As for the Code 42........seems only to happen when you get a little higher in th rpms. I could usually avoid CE light untill i got aggresive or jumped on the highway. The light bugged the shit out of me, but so did driving calm, or going slow. kicks in after you hit a certain rpm range for a certain amount of time.

Also, going to the shop to have this piece replaced is a good 1000$ job.
At least it is here.
 

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Discussion Starter #27
if you were alone, that is not a bad time at all.
Thanks! I feel better because I thought I was EXTRA slow doing that. I wanted to do it in 1 hour. Putting it in on the other hand is a little more tedious and much more time involved if you can't line up the splines correctly.


Nice Write Up.
Gaskets a good idea.
As for the Code 42........seems only to happen when you get a little higher in th rpms. I could usually avoid CE light untill i got aggresive or jumped on the highway. The light bugged the shit out of me, but so did driving calm, or going slow. kicks in after you hit a certain rpm range for a certain amount of time.

Also, going to the shop to have this piece replaced is a good 1000$ job.
At least it is here.
Thank you!
Now that you bring that up, I do remember that it came on above 2500 rpms.
Silly me! :kekekegay
I wonder if it would be cheaper to fly me up there to do the job for you?
Maybe a $500 or $600 round trip ticket? That would be quite fun indeed, that is if you were going to pay $1000 to do it. :sadsmilie

The clip was $1.80, output shaft seal was like $10, and the gasket was about 5 or 7 bucks. It's definitely worth getting those if you have it off.
 

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Discussion Starter #29
Found these, thought it would go nice in this thread.


Some Speedo gear part numbers from Jeff Watson:
http://forums.celicasupra.com/showthread.php?t=3634&highlight=speedometer+part


Well Gentlemen,

Well, the first portion of the response is for informational purposes only - unless you are bored one night and feel like doing some mathematical computations. The primary variables utilized in speedo gear determination is speedo and tire revolutions per mile (RP/Mile), along with tire height and gear ratio. The computation matches 1000 speedo RP/mile to (x) tire RP/Mile. This ratio of course factors in tire height and axle gear ratios. It goes something like this...

Speedo Gear Calculator

1.) Determine Tire Diameter ( 225 x 60 x 14) = 24.63"
2.) Multiply Tire Dia. by pi ( 24.63 x 3.1416 ) = 77.38 tire circumference
3.) Divide one (1) mile into inches or multiply yards by inches (1,760 yards x 36 inches ) 63,360
4.) Divide 63,360 by 77.37 ( 63,360 / 77.38 ) = 818.8 RP/Mile of tire
5.) Multiply tire RP/Mile by Axle Ratio to determine driveshaft RP/Mile ( 818.8 x 4.30 ) = 3,521
6.) Divide by 1000 speedo RP/Mile (3,521 / 1000) = 3.521 (Round this number to 3.5 - this is the ratio you want to achieve).

You will now need to research the available gear ratios for your tranny and determine which combination will work best. My 86 Supra came with a 4.30 rear gear and a 35/10=3.5 speedo gear set. When I went to the 3.90 rear gear I chose the best available speedo set which was the 31/10=3.10. After doing the calculations I found myself at an actual ratio of 3.19, which ends up at a 2.8% error (3.10 / 3.19) x 100 = 97.2 or 2.8%. After correcting for my taller tires (25.1") I recalculate a speedo error of only 1.0%. Supposedly +/- 3.75% is an acceptable error percentage. This equates to 3/8 of one mile error for every ten (10) miles traveled.

I made a more thorough presentation the first time, but hopefully this still helps in your quest to find the proper speedo gear sets. If someone would like, please save this info for others that would like the reference.

Regards,

Carlos

(from: http://forums.celicasupra.com/showthread.php?t=10668&highlight=speedometer+part&page=2 )
 

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Okay so im going to be that guy and ask the question.. Does all this have to be done because just replacing the speedometer elbow gear isnt enough to have the speedometor to work again. I used the drill test on the speed cable and the speedometer worked. I am hoping i dont have to drop the whole transmission just to get the needle to move.

Or did i read that this tutorial was to replace something else in the transmission that was broke?

Jesus
 

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If the elbow works and spinning the speedo cable with a drill works the speedo, then this is required. The spring slips off with age and use, and the gear slides away from the elbow. A bit gettho but I used rtv to hold the gear in place once.
 

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I just went to SILV and on the last day my speedo went out. Threw a code 42 the whole way home (vegas to Phx). The gas mileage was not bad. but after 4 hours of driving the car would stalled when I got off the freeway but started right up. I just pulled the elbow and all the stuff is good up to the speedometer. Felt inside the tranny and can move the drive gear on back and fourth. Great writeup on this post. Now I have to do all this work to replace a 2 dollar clip. Funny I was just thinking about changing the tranny fluid. Looks like the car is down for a while. Before SILV the car was down for three weeks doing a differential rebuild, rear wheel bearings and CV axels.
 

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Hi everyone, can the drive unit in the dash unit wear/break? I have the digital dash (UK car) and the elbow works fine, and cable rotates if the rear wheels are rotated but the cable seems to only engage inside the dash unit temporarily (a speed is briefly shown then drops to zero again).

I am fearful that there is wear inside the dash and this is not repairable.

I have not dared try to take the dash apart yet so does anyone have experience of this issue before I attempt some surgery!

Thanks.
 

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If you can see the cable spin when the wheels are moving then its is your dash. The dash panel is not hard to remove from car. It is just a few screws. As for tearing it apart just be carful and remove all the screws. Ensure you have a nice neat place to perform this work. I would suggest getting a new dash from a junk yard or somewhere and try that first. Never tore apart a digital panel before.
 

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subscribed (speedo inop for months now)
 

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I have had the dash out before but the thought of breaking into the actual gauge unit is putting me off. The chances of finding another dash in a junk yard over here in the UK is remote - not enough MA61's left on the road. Thanks anyway - I might fit an aftermarket digital speedo but its a shame that the 80s display is permanently stuck on zero.
 

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I have had the dash out before but the thought of breaking into the actual gauge unit is putting me off. The chances of finding another dash in a junk yard over here in the UK is remote - not enough MA61's left on the road. Thanks anyway - I might fit an aftermarket digital speedo but its a shame that the 80s display is permanently stuck on zero.
You might try installing an mpguino like i did, there is a page where you can display the speed real time but it also takes info like how long the injectors are open, rpm's, etc to do math for mpg all with trip meters and such. Very cool for the price. You can always run that until you source a new cluster. I've put close to 10k miles on mine and love it.
http://www.celicasupra.com/forums/showthread.php?84905-MPGuino-and-cluster-to-cruise-control-vss
 

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I just got my first Supra. I've had a GT and one of the rare 83 GT/GT-S coupes (the test platform that year). I'm not sure if someone swapped out the rear end or what. My speedo works but is off by a lot. It has to read 86 mph to achieve 70 mph. It's racking miles up on the speedo faster than it should as a result.

Any ideas?
 

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Check the odometer. Old Speedos are often out by quite a bit. But the odometer will still be bang on accurate. If the odometer is also off then the gearings has been changed. You'll need to drive pretty far on the highway to get a big enough reading to be sure, and you can use mile markers. Or lay under the car and count the rotations of the driveshaft and axles(make sure the axles turn at the same speed. The firewall data plate will show you what gearing the car came with.
 
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