Throttle Position Sensor
Thread Starter
Racer
Joined: Sep 2004
Posts: 323
Likes: 1
From: Muncie Indiana
Throttle Position Sensor
My car is upshifting early so I had a transmission shop do a diagnostic and they said the tps was only using 3 volts but the ecm was putting out 5 volts. They wanted $150.00 to replace the switch so I thanked them and went to Advance Auto Parts for $19.95
Here's my question when I put the new switch on I have to rotate it about 1/4 turn towards the front of the car in order to engage the shaft. Then rotate it back in order to put screws in to hold it in place. This appears to preload the switch. Should I make some kind of an adjustment to the cable assembly on the other side so that switch goes on straight and lines up with mounting holes? Or is it normal to have to preload the switch this way?
Here's my question when I put the new switch on I have to rotate it about 1/4 turn towards the front of the car in order to engage the shaft. Then rotate it back in order to put screws in to hold it in place. This appears to preload the switch. Should I make some kind of an adjustment to the cable assembly on the other side so that switch goes on straight and lines up with mounting holes? Or is it normal to have to preload the switch this way?
Thread Starter
Racer
Joined: Sep 2004
Posts: 323
Likes: 1
From: Muncie Indiana
Originally Posted by Bill's86Coupe
Yepppers...have to get the throttle and tps to work together so it does have to install the way you did it.
Let us know if this new TPS fixed the problem or not.
Let us know if this new TPS fixed the problem or not.
I also suspect that the $150.00 the transmisssion shop wanted was not for the tps but to do some type of internal service to the transmission. Because they knew that the tps would not change the shift points. I might have been more inclined to have them do it if they had just been honest about what they would do and not just point at the tps and say that's the problem.
Instructor
Joined: Dec 2004
Posts: 142
Likes: 0
Sounds like your line pressure cable (the cable connected to the TB that goes to the transmission) might be out of adjustment. They will probably tighten it up to induce more line pressure before shifting (thus shifting at a higher RPM).
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Le Mans Master
Joined: Apr 2000
Posts: 5,713
Likes: 105
From: Manassas VA
Well on a 93 the shifts are controlled by the govenor and the tv cable. The only control the computer has with the transmission is torque converter lock up.
If a transmission shop told you that the tps controls shifts on a 93 you need to go to a different shop.
If a transmission shop told you that the tps controls shifts on a 93 you need to go to a different shop.
Intermediate
Joined: Sep 2005
Posts: 39
Likes: 0
From: Ok
I was under the impression that the TPS had to be adjusted on the screws until a reading of .525 volts was obtained, I know I did this on mine a while back because my tickover speed was 200rpm too high, after setting the tps to .525 ( well actually it was .532) I got the tickover down to what it should have been...but then mines an 89, it may be dif on a 93, if it is, sorry for butting in
Le Mans Master
Joined: Apr 2000
Posts: 5,713
Likes: 105
From: Manassas VA
Originally Posted by ddanks
I was under the impression that the TPS had to be adjusted on the screws until a reading of .525 volts was obtained, I know I did this on mine a while back because my tickover speed was 200rpm too high, after setting the tps to .525 ( well actually it was .532) I got the tickover down to what it should have been...but then mines an 89, it may be dif on a 93, if it is, sorry for butting in
The older ones are adjustable, but the LT1 is fixed. There are some people who have oblonged the hole for adjustment, but still this will have no effect on transmission shifting of a non electronic version.
There is some confusion as to when the 4L60E transmission went into production. On some GM vehicles the 93 got it, but all automatic corvettes were non electronic controlled transmissions.
The 2 easiest ways to verify this IMO is,
1. do you have a ECM or PCM controlled car? ECM cars do not have the ability to control the transmission.
2. do you have a tv cable which goes from the asr module down to the transmission. PCM cars do not have the cable.
Thread Starter
Racer
Joined: Sep 2004
Posts: 323
Likes: 1
From: Muncie Indiana
Adjusted the TV Cable
I had the car down while doing front brakes so I tried a TV adjustment. I put a 1/8 drill in the holes released all three cables. Sit my torque wrench at 8 NM pulled the slack out of the cables and locked the tv cabel before releasing the pressure on the torque wrench. The I got in the car and went WOT. I heard the other two cables adjust and lock themselves. I removed the drill and buttoned the ASR up. The shift point is about 5100 RPM from 4700RPM at WOT. The upshifts are a little firmer but certanely not objectionable. 
Race Director
Joined: Jul 2001
Posts: 14,604
Likes: 3
From: Glendale, AZ
i need to do the same thing i think - do you think you could do a "picture included write up"
and point out those holes you put a drill in?
that coufuses me? do you mean just a drill bit? or a bit loaded in a drill?
and point out those holes you put a drill in?
that coufuses me? do you mean just a drill bit? or a bit loaded in a drill?
Originally Posted by John Robinson
I had the car down while doing front brakes so I tried a TV adjustment. I put a 1/8 drill in the holes released all three cables. Sit my torque wrench at 8 NM pulled the slack out of the cables and locked the tv cabel before releasing the pressure on the torque wrench. The I got in the car and went WOT. I heard the other two cables adjust and lock themselves. I removed the drill and buttoned the ASR up. The shift point is about 5100 RPM from 4700RPM at WOT. The upshifts are a little firmer but certanely not objectionable.
