So got the front end put back together, hood/bumper/tires put on, car off jackstands. Put the car in reverse to back it out of the garage, no explosion so I think I'm onto something. Put it in drive, shifts/moves smooth as butter coming out of the alley. Get it on the side street and start it rolling down the road annnnnnnnnnnnnd, no shift. Took it out on Main St. and got it to a fast enough speed that it should be in 3rd and still in first. No slipping, no weird noises, just holds first like I'm driving a manny tranny.
After a couple of days of troublshooting and test driving, found that very rarely it will shift to 2nd. Even more rarely, it'll shifts, albeit as a skip, from 2nd to 4th. Rarest of all, it starts out in 4th.
Little history: Supposedly, seller said it was a rebuild for his Comp G that never got installed because it burned to the ground from a recall issue (Similar to our awesome little predecessors) so it was sitting around in his garage (he works as an engine mechanic at a shop that has a transmission rebuilder in house who did the rebuild for him). Said he got it out of a GTP and after the rebuild, was going to swap the valve body to use the paddle shifters but in that limbo moment, the car burned up before he got that far. Gave me a 1 month labor and 6 months part warranty.....that was 4 months ago.
I was told the TVC as I don't remember unhooking such a thing when removing the old trans or rehooking it up when I put in the current trans. I've searched online for what this looks like and can't find any pics or mention of it. Some have said the speed sensor either not being hooked up (which it is) or faulty (haven't tried to replace it yet). Any ideas from the good folks at PFF?
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03:27 PM
PFF
System Bot
Darth Fiero Member
Posts: 5922 From: Waterloo, Indiana Registered: Oct 2002
What is the PCM reporting coming from the vehicle speed sensor? Is it accurate to actual?
Are any trouble codes set?
-ryan
Hey Ryan,
I've not had a chance to do any scanning as I don't possess a scanning tool YET. I am going to get my hands on the ScanTool.net OBX SX software. Should be enough to let me do some mild troubleshootin'.
I went and had the codes pulled at AutoZone (couldn't wait til I got my scanner in the mail). Came back both the TPS and VSS. Now, the TPS never threw a code before I replaced the tranny and fella at AZ to said that if one is faulty, it causes the PCM to think the other is faulty (doesn't sound right to me but it wouldn't be the weirdest thing of which I've ever heard).
So bought a replacement VSS but didn't buy the replacement TPS because it's a N* TB and I have no idea which year make model from which the TB came. When I find out and replace the TPS, if it doesn't resolve the issue, then it's safe to assume that either my wiring harness is faulty (good chance as it's melted some from the header's heats on the side opposite to the trunk....plan on rebuilding harness during the winter anyway) or, as Ryan told me earlier today, my PCM isn't programmed properly for the TPS.
[This message has been edited by akademikjeanius (edited 10-04-2011).]
Check to make sure you have the +5 volt reference on the TPS grey wire, it should also be on the MAP but the TPS one missing will cause similar problems. On 98 engines it comes from C2 pin 33 along with other sensors using the +5 volt ref I believe and on the 99 up it has it is on the same pin all by itself for just the TPS. The PCM uses TPS info to control shifting. Dan
Check to make sure you have the +5 volt reference on the TPS grey wire, it should also be on the MAP but the TPS one missing will cause similar problems. On 98 engines it comes from C2 pin 33 along with other sensors using the +5 volt ref I believe and on the 99 up it has it is on the same pin all by itself for just the TPS. The PCM uses TPS info to control shifting. Dan
Dan,
Thanks for the advice.
Does it make a difference that the engine is a Series III?
No difference because you are using a series II PCM along with the N throttle body so the PCM is still looking for info on throttle position to control the shift points and how hard to shift. Dan
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08:31 AM
Darth Fiero Member
Posts: 5922 From: Waterloo, Indiana Registered: Oct 2002
If you could post a picture of your Northstar throttle body, I might be able to tell you what year Northstar it came off of in the case you need to get a new TPS.
THe TPS was the culprit on a swap a did a few years back...The trans would not shift into 4rth but never did throw a code for the TPS...Swaped it out and trans shifted perfect and the swap ran strong....
No difference because you are using a series II PCM along with the N throttle body so the PCM is still looking for info on throttle position to control the shift points and how hard to shift. Dan
Awesome! I planned on testing it today before work but got over to my friend's house (where I was doing the tranny job) and realized I left the garage door opener at my house. :P Will jump on it first thing tomorrow.
*NOTE* I was reading this tech article on symptoms of a bad tps and testing it w/ a voltmeter. Ryan mentioned testing this way but was able to go in detail as I caught him in the middle of something he was doing but I'm grateful as it got me going in the right direction on how to test and possibly resolve.
quote
Originally posted by Darth Fiero:
Exactly what TPS code number did you get?
If you could post a picture of your Northstar throttle body, I might be able to tell you what year Northstar it came off of in the case you need to get a new TPS.
-ryan
Unfortunately, I didn't get the print-out from the guy @ AZ who did the scan for me (rushing before having to switch cars and head to work) and before I left it over my old mechanics house, I took the battery out in case somebody decided they wanted to joyride, thus clearing the codes.
Thanks for taking a stab at identifying the TB. Has me stumped. Called Dementia today and talked about everything BUT what I originally called to ask him: If HE knew which year/make/model(s) it was from. I will take several pics of it and post them tomorrow.
quote
Originally posted by MstangsBware:
THe TPS was the culprit on a swap a did a few years back...The trans would not shift into 4rth but never did throw a code for the TPS...Swaped it out and trans shifted perfect and the swap ran strong....
Thanks for the input!
I am 50/50 on believing it's the TPS because it never threw a code when previous trans was in there. I figured the VSS was more likely but I put its replacement in before I came to work today and no change. Funny thing is I can't make it shift going through the range of gears manually with the shifter. As soon as I determine which TB I have, I'll swap it A.S.A.P.
The VSS will generate AC voltage that will vary from 0.5 volts at 100 output shaft rev's per min to more than 100 volts at 6000 output shaft rev's per min.
The VSS will not produce any signal with the car sitting still. But you can test it with an ohm meter (disconnect from PCM/wiring prior to doing this ohms test). Should be between 981 - 1864 ohms.
If the resistance test checks out, then reconnect the PCM harness, set your DVM (digital volt meter) to measure AC voltage, and tap into the VSS wires. When the output shaft starts turning, you should see voltage start climbing on your DVM. If you see no voltage, disconnect the sensor from the PCM harness and connect the DVM directly to the sensor and run the test again. If no voltage is generated by the sensor with the wheels turning, then you either have a bad sensor or it is not reading the spinning reluctor wheel on the differential inside the transmission for some reason.
Can you please post exactly what trouble code number you got for the TPS?
