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Discussion Starter · #1 ·
I did some searching but did not find the answer I was looking for...

My speedo has recently gone haywire. Sometimes it works, but mostly it bounces around or doesn't work. I haven't checked yet, but I assume this is likely the cable at the tcase being rounded off. Waiting for some warmer weather to get under there.

Now I've noticed that the viscous coupling (overdrive/5th gear) doesn't always engage. I end up at mid/high 2000s RPMs on the highway at 65mph.

I know it's supposed to engage around 55mph, so I'm wondering if this is linked to my speedo issues.

Does anyone know if the viscous coupling is engaged based upon the speedo reading? and if these two issues are likely linked?

Thanks!
 

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I would guess they are linked. You however have your terminology wrong. You are describing the lock up torque converter not the VC. The VC is the unit in the transfer case which controls the drive between the front and rear axle. The torque converter is the link between the engine and transmission. The computer needs a speed signal to control the lock up function of the torque converter.
 

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Your transmission has no electronics whatsoever. So the problems are not linked.
To work out whether it is your speedo gauge, or the sender/cable, simply use your cruise control. Your cruise control works off the same signal and therefore if it maintains speed alright it means that the signal side of things are OK.
 

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Discussion Starter · #4 ·
Thanks for the clarification.

So, the cruise doesn't work, (which it did before) then this would suggest that the both the cruise control and the torque converter are not getting a speed signal. And it's plausible that this would be caused by the faulty speedo cable, correct?

Thanks!
 

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Thanks for the clarification.

So, the cruise doesn't work, (which it did before) then this would suggest that the both the cruise control and the torque converter are not getting a speed signal. And it's plausible that this would be caused by the faulty speedo cable, correct?

Thanks!
Your speedo and transmission issues are NOT related.

First test with the torque convertor is the stall test. Put the car in drive and your foot hard on the brake. Try taking the engine up to around 2000rpm while keeping the brakes hard on. The Motor should start to die around 2,000 rpm are the torque convertor start to fully engage.

Needless to say that you only do this test with plenty of space in front of you in case the brakes do not hold, etc.

Do not hold it near 2,000rpm for long, it will overheat your transmission.
 

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I stand corrected p76 is right and there is no connection between the torque converter and the speed signal. the torque converter lock up is purely hydro-mechanical. sorry for any confusion i may have caused.
 

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Discussion Starter · #7 ·
So I performed the torque converter test. Peaked at 2000rpm, so that's a good sign. I was even able to use my cruise the other day while the speedometer was behaving briefly. I believe the torque converter was working during that drive as well.

I guess I just have to fix the speedo cable thing and go from there.

Thanks everyone.
 
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