l67ss Posted October 30, 2013 Report Posted October 30, 2013 Found a switch in an early 90s gp 3.1 auto that said second gear start. Whats that about? Quote
Pontiac6KSTEAWD Posted October 30, 2013 Report Posted October 30, 2013 Mainly for winter driving, but it puts the tranny into second gear, instead of first, for trying to get out of snow/mud. Quote
rich_e777 Posted October 30, 2013 Report Posted October 30, 2013 Always wondered about that myself:thumbsup: Quote
WhatTheFehl Posted October 30, 2013 Report Posted October 30, 2013 I think this was mentioned in a thread just recently. Yes it puts the transmission into second gear, but it is important to note that while in that mode it just uses second gear as low gear. It will still shift through 3rd and 4th gear once you get going. And yes it is designed for use in slippery conditions, it makes it more difficult to spin out, and gives you more traction to get going. Think of it as a very early, rudimentary and cheap version of traction control. Quote
RobertISaar Posted October 30, 2013 Report Posted October 30, 2013 keep in mind, your PCM will have to support such a mode to use it correctly. AFAIK, no OBD2 cars did. Quote
will_s95 Posted October 30, 2013 Report Posted October 30, 2013 I actually find this feature pretty handy. In the year that I've had my GP, I have never once been stuck, and that's saying a lot for Minnesota. Quote
WhatTheFehl Posted October 30, 2013 Report Posted October 30, 2013 I used it a few times when I had my 95. Quote
l67ss Posted October 30, 2013 Author Report Posted October 30, 2013 It was in a dirty but otherwise identical car to yours I actually find this feature pretty handy. In the year that I've had my GP, I have never once been stuck, and that's saying a lot for Minnesota. Quote
Crazy K Posted October 31, 2013 Report Posted October 31, 2013 keep in mind, your PCM will have to support such a mode to use it correctly. AFAIK, no OBD2 cars did. 1996 GP??? they all had it. My 96 has it wired in, but running a 97 GP PCM(NA 3800, 4t60e) means it hasn't been tested. What's the worse that would happen if it doesn't work, Robert? Quote
RobertISaar Posted October 31, 2013 Report Posted October 31, 2013 PCM might set a trouble code? otherwise, no idea. if it happens to use the same pin as performance shift(which it almost always did for OBD1 applications), then it would cause that to come into effect. internally, the PCMs didn't change that much until 98 other than the obvious 256 vs 512 BIN size, so the sampling circuit is likely identical for that circuit. Quote
l67ss Posted October 31, 2013 Author Report Posted October 31, 2013 That brings up another question, what about a performance shift button? U have a hole in my new console (traction control) that i wanna fill PCM might set a trouble code? otherwise, no idea. if it happens to use the same pin as performance shift(which it almost always did for OBD1 applications), then it would cause that to come into effect. internally, the PCMs didn't change that much until 98 other than the obvious 256 vs 512 BIN size, so the sampling circuit is likely identical for that circuit. Quote
RobertISaar Posted October 31, 2013 Report Posted October 31, 2013 if the calibration supports it, wire it up and it should work. Quote
gambler87 Posted April 6, 2014 Report Posted April 6, 2014 Robert I have a quick question about the 2nd gear start thing. I put a 97 PCM and a 97 wiring harness into my 96 Gtp. Now I have a constant 2nd gear start light. Do u know what pin in the ecu and also what pin that might be on the trans that I would need to change to be able to get rid of that light Sent from my XT1080 using Tapatalk Quote
RobertISaar Posted April 6, 2014 Report Posted April 6, 2014 from what i can see..... the 2nd gear start switch directly controls both the request line to the PCM and the bulb in the cluster. for some reason, the circuit is grounded constantly. on a 96 GTP, looks like the signal wire goes through pin J1 on the C100 connector, then to the PCM's pin 33 on the clear connector(C2). on a 97 Z34, pin J1 on the C100 is for fuel level signal(from the PCM to the cluster). 97 Z34 doesn't appear to use PCM C2-33 at all. Quote
gambler87 Posted April 6, 2014 Report Posted April 6, 2014 So technically I could unpin the j1 on the car side of the c100 and then find the performance shift wire at the car side c100 and Repin that into the j1 pin and use my 2nd gear start switch for performance shift mode? Sent from my XT1080 using Tapatalk Quote
RobertISaar Posted April 6, 2014 Report Posted April 6, 2014 possibly, assuming there is a performance shift function with your PCM and the engine-bay side of the C100 harness is already setup for it. Quote
ManicMechanic Posted April 6, 2014 Report Posted April 6, 2014 Ken and Saar: Could I add this to my van? *1995 Olds 4T60E Quote
RobertISaar Posted April 6, 2014 Report Posted April 6, 2014 5B(94-95 S1 3800, N/A and S/C) seems to have 3 transmission modes: normal, cruise and sport. effects shift points and TCC apply/release thresholds. so, yes, it could be added in, but i couldn't tell you what the PCM will do with the U-van calibration. some "sport" modes were actually 2nd gear start, others were actually sport-looking. Quote
gambler87 Posted April 7, 2014 Report Posted April 7, 2014 I have a 97 Monte Carlo ecu with a 97 Monte tune in it right now. And it has a cruise,sport,performance shifting tables. It also have good fuel and bad fuel tables both. The car side engine harness does have a performance shift wire Sent from my XT1080 using Tapatalk Quote
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