What's This Switch For ?
Thread Starter
Le Mans Master
Joined: Feb 2005
Posts: 6,494
Likes: 566
From: Clearwater Florida
What's This Switch For ?
..... There is a micro switch on the rear of the '87 A4 shifter that is open 'til the shifter is put into 3rd , 2nd , or 1st gear ... this must be for ECM purposes ... maybe TCC ? ... I can't find anything descriptive about it in the Factory Service Manual ... I installed a B&M Megashifter in the car yesterday and can't find any way to mount and/or activate this switch ... I kinda hate to eliminate something when I am not real clear about what its for ... especially on computer controlled cars ..................
Team Owner
Joined: Dec 1999
Posts: 34,873
Likes: 487
From: Lacey WA RVN 68-69
NCM Sinkhole Donor
The only thing in the FSM for a switch on the shifter assembly is called a "transmission position switch" Look in the Electrical Diagnosis manual on page 8A-201-8 in Figure A. It's not very clear where the switch is located on the shifter.
Your pic shows a switch that appears to be new given the dark color of the shifter; did you replace it?
Your pic shows a switch that appears to be new given the dark color of the shifter; did you replace it?
Thread Starter
Le Mans Master
Joined: Feb 2005
Posts: 6,494
Likes: 566
From: Clearwater Florida
The only thing in the FSM for a switch on the shifter assembly is called a "transmission position switch" Look in the Electrical Diagnosis manual on page 8A-201-8 in Figure A. It's not very clear where the switch is located on the shifter.
Your pic shows a switch that appears to be new given the dark color of the shifter; did you replace it?
Your pic shows a switch that appears to be new given the dark color of the shifter; did you replace it?
..... The switch is original ... the photographer is lousy ......
..... The switch in the pic is open until the shifter gets to 3rd gear or lower ... in other words no contact in P N R OD ...... that just seems odd ... which is why I asked , 'cause I don't want to screw anything up by disconnecting something important ............
Le Mans Master
Joined: Aug 2000
Posts: 8,838
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From: Australia
Safety Car
Joined: Nov 2004
Posts: 4,991
Likes: 5
From: The Pines South Jersey
From my 86 Helms
Sections 6E3-C8-1 & 6E3-C8-2 Drivability and emissions
AT Overdrive switch
used by the ecm in OD to control clutch applies and releases, the trans doesn't have to be in OD to apply the clutch (TCC)
Figure C8-2 shows how to adjust it
More on how and when it comes into play shown in Chart C-8A
It's all about fuel economy and driveability - from what I read you can close the switch and TCC will occur @ 40mph or if you custom burned your chip what ever is set at.
So in a nut shell, jumping it out or manually closing the switch (closed in drive) may be just fine for you - by doing this TCC engagement will be delayed to that mph set point mentioned above.
For me I do this anyway by keeping it in Drive until I'm on a highway or interstate, because I hate lugging around in OD
Sections 6E3-C8-1 & 6E3-C8-2 Drivability and emissions
AT Overdrive switch
used by the ecm in OD to control clutch applies and releases, the trans doesn't have to be in OD to apply the clutch (TCC)
Figure C8-2 shows how to adjust it
More on how and when it comes into play shown in Chart C-8A
It's all about fuel economy and driveability - from what I read you can close the switch and TCC will occur @ 40mph or if you custom burned your chip what ever is set at.
So in a nut shell, jumping it out or manually closing the switch (closed in drive) may be just fine for you - by doing this TCC engagement will be delayed to that mph set point mentioned above.
For me I do this anyway by keeping it in Drive until I'm on a highway or interstate, because I hate lugging around in OD
Last edited by _twisted_; Nov 21, 2011 at 04:29 AM.
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Thread Starter
Le Mans Master
Joined: Feb 2005
Posts: 6,494
Likes: 566
From: Clearwater Florida
From my 86 Helms
Sections 6E3-C8-1 & 6E3-C8-2 Drivability and emissions
AT Overdrive switch
used by the ecm in OD to control clutch applies and releases, the trans doesn't have to be in OD to apply the clutch (TCC)
Figure C8-2 shows how to adjust it
More on how and when it comes into play shown in Chart C-8A
It's all about fuel economy and driveability - from what I read you can close the switch and TCC will occur @ 40mph or if you custom burned your chip what ever is set at.
So in a nut shell, jumping it out or manually closing the switch (closed in drive) may be just fine for you - by doing this TCC engagement will be delayed to that mph set point mentioned above.
For me I do this anyway by keeping it in Drive until I'm on a highway or interstate, because I hate lugging around in OD
Sections 6E3-C8-1 & 6E3-C8-2 Drivability and emissions
AT Overdrive switch
used by the ecm in OD to control clutch applies and releases, the trans doesn't have to be in OD to apply the clutch (TCC)
Figure C8-2 shows how to adjust it
More on how and when it comes into play shown in Chart C-8A
It's all about fuel economy and driveability - from what I read you can close the switch and TCC will occur @ 40mph or if you custom burned your chip what ever is set at.
So in a nut shell, jumping it out or manually closing the switch (closed in drive) may be just fine for you - by doing this TCC engagement will be delayed to that mph set point mentioned above.
For me I do this anyway by keeping it in Drive until I'm on a highway or interstate, because I hate lugging around in OD
... Thats it ! ... I previously read the descriptive on C8-1 but didn't flip the page to see C8-2 ... until then things were rather vague about which switch was being referred to as there are some wires in the neutral safety switch harness that send info to the ECM ............. Thanks for clarifying ! ...........
