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Auto to Manual Swap Questions, Need help

Joined
24 February 2013
Messages
35
Location
Tampa, FL
Hey Guys need some help, having some issues and thought the brains of NSXPRIME could lend some thoughts to figure this out.

I just did the full auto to Manual Swap on a 1996 Coupe ODB2, but there are some bugs I need worked out.

I upgraded to a 6 speed transmission from a 2003, very low miles so It was a no brainer as you can’t find any working Auto transmissions anywhere and no parts to fix them.

I searched a ton of threads that I could find and comments in those threads, pasted together a knowledge base for me to work with.

We sourced all OEM parts for this conversion the only thing that was not OEM was the 6 foot long clutch hose from the master to the slave. And the Brand new Dual Clutch is from SOS..Exedy twin organic 425 clutch and flywheel. Since it’s such a strong diaphragm the clutch engages a few inches from the floor, tried adjusting the plunger length but it’s really low… At a dead stop it feels like the slave piston is not pushing the clutchdiaphragm very far and its feels like more effort to get the car into reverse. Driving it shifts perfect once you accept the low engagement.

After we started the car it had errors, The TCS error light and Check engine light are on.

Scanned the ODB2 and we are getting all transmission codes.

P0700 transmission Control System ( Malfunction ) indicator lamp request.

P1753, P1758, P1705, P1768

P0753 Shift Solenoid A Electrical

P0758 Shift Solenoid B Electrical

P0740 Torque Converter Clutch Solenoid Circuit Open

Also, No Reverse lights, where do I get that signal from and where would I re-route the signal to…?

(C425/6) C425/8).C499/4 to C499/3C499/11 to C425/10C425/11 Gry/WhtC425/11 to hand parking brake, these pigtails are mis-numbered or the person typing them in the thread got the numbers wrong and or colors of the wires wrong.

We purchased cams from a manual and the matching ECU and will put them in when we do the timing belt and water pump one day… as well as the throttle body and throttle cable just in case the Auto ECU would give us problems.. Other than the ECU not knowing its manual now, how can we short or trick the ECU to think everything is ok down there.



Also, the car has developed a hesitation, or miss. It is happening every 3 seconds, and is noticeable from by feeling the acceleration/deceleration when it hesitates, plus you can hear the miss in the exhaust notes.

So no Cruise Control ( cancel signal )… does it need the second Switch on the clutch pedal or brake pedal?

How does the Manual Transmission let the Auto ECU know its in reverse? What Pigtail?? C499? Or C425? And what wire/number?

When re-routing do I reroute before or after the pigtails?

I Have the paperback NSX manuals for all the NSX years in the shop, page after page tring to figure it out.

Help a Fellow NSXer out guys. Or someone in Japan that has done this swap can you reach out please.
 
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and I believe this is the part number to the "shift cage" 54151-SL0-980

and shift cable 54315-SL0-981
 
When I did my conversion, I got a complete shift assembly and cables from AH Parts Dismantlers in Sacramento, CA. Mine came off of this wrecked 1999:

IMG_0005.jpg

It was FAR less expensive than ordering new from Japan. Id' have to go back to my spreadsheet, but I think it was $50 for the whole assembly. I just ordered all of the rebuild pieces from Honda and refurbished it.

IMG_2613.JPEG
 
54151-SL0-A01 is the difference for LHD and RHD.

That base can be converted from AT to MT at significant cost savings as it is the same basic part.

I am presuming OP is LHD.

I recommend OP DM me for my DIY

(I'm on a plane back to NZ, so short responses. )
 
Last edited:
When I did my conversion, I got a complete shift assembly and cables from AH Parts Dismantlers in Sacramento, CA. Mine came off of this wrecked 1999:

View attachment 190269

It was FAR less expensive than ordering new from Japan. Id' have to go back to my spreadsheet, but I think it was $50 for the whole assembly. I just ordered all of the rebuild pieces from Honda and refurbished it.

View attachment 190270
I cant post new threads could you help me... need this posted in the general help section? when I try to post It says error.. maybe I have the wrong browser or something


Hey Guys need some help, having some issues and thought the brains of NSXPRIME could lend some thoughts to figure this out.

I just did the full auto to Manual Swap on a 1996 Coupe ODB2, but there are some bugs I need worked out.

I upgraded to a 6 speed transmission from a 2003, very low miles so It was a no brainer as you can’t find any working Auto transmissions anywhere and no parts to fix them.

I searched a ton of threads that I could find and comments in those threads, pasted together a knowledge base for me to work with.

We sourced all OEM parts for this conversion the only thing that was not OEM was the 6 foot long clutch hose from the master to the slave. And the Brand new Dual Clutch is from SOS..Exedy twin organic 425 clutch and flywheel. Since it’s such a strong diaphragm the clutch engages a few inches from the floor, tried adjusting the plunger length but it’s really low… At a dead stop it feels like the slave piston is not pushing the clutchdiaphragm very far and its feels like more effort to get the car into reverse. Driving it shifts perfect once you accept the low engagement.

After we started the car it had errors, The TCS error light and Check engine light are on.

Scanned the ODB2 and we are getting all transmission codes.

P0700 transmission Control System ( Malfunction ) indicator lamp request.

P1753, P1758, P1705, P1768

P0753 Shift Solenoid A Electrical

P0758 Shift Solenoid B Electrical

P0740 Torque Converter Clutch Solenoid Circuit Open

Also, No Reverse lights, where do I get that signal from and where would I re-route the signal to…?

(C425/6) C425/8).C499/4 to C499/3C499/11 to C425/10C425/11 Gry/WhtC425/11 to hand parking brake, these pigtails are mis-numbered or the person typing them in the thread got the numbers wrong and or colors of the wires wrong.

We purchased cams from a manual and the matching ECU and will put them in when we do the timing belt and water pump one day… as well as the throttle body and throttle cable just in case the Auto ECU would give us problems.. Other than the ECU not knowing its manual now, how can we short or trick the ECU to think everything is ok down there.



Also, the car has developed a hesitation, or miss. It is happening every 3 seconds, and is noticeable from by feeling the acceleration/deceleration when it hesitates, plus you can hear the miss in the exhaust notes.

So no Cruise Control ( cancel signal )… does it need the second Switch on the clutch pedal or brake pedal?

How does the Manual Transmission let the Auto ECU know its in reverse? What Pigtail?? C499? Or C425? And what wire/number?

When re-routing do I reroute before or after the pigtails?

I Have the paperback NSX manuals for all the NSX years in the shop, page after page tring to figure it out.

Help a Fellow NSXer out guys. Or someone in Japan that has done this swap can you reach out please.
 
Time will be carved to study the manuals. If they are not in the Library, then DM me and we'll get what you need...you'll just have to promise to document this for the next person.


You are going to have to make a custom harness that interfaces to the reverse lights, transmission neutral switch, and shift position. I don't cut factory wires, so I built a custom interface harness that goes from the shift selector area to the rear LH bulkhead.

Fancycraft probably has what you need. https://fancy-craft.firebaseapp.com/

DO NOT run any additional wires from inside the passenger compartment to the engine compartment. Rather repurpose the AT connectors to the MT neutral switch as such. You will have 2x extra connectors for the solenoid control, use salvaged connectors to cap them.

As for OBD2: it will be a challenge. You will have to either disconnect the AT ECU or simulate the I/O. The six speed lock out also needs to be done.
 
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