Start trouble after converting transmission from automatic to manual

GEORGE DONAHOE

MEMBER
1999 CHEVROLET SILVERADO
5.3L
V8
4WD
MANUAL
337,000 MILES

Converted transmission from automatic to five speed, now it is all manual before everything was electronic and push button. The engine will not turn over. I can jump it over at starter it cranks but will not stay running. I need to bypass neutral switch safety circuit to get it to run. Not sure what else. Thank you in advance. Really need my work truck back to work.

5 Replies

WRENCHTECH

MECHANIC
20,758 POSTS

Did you change the steering column or ignition switch?

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Monday, December 25th, 2017 AT 2:00 PM

GEORGE DONAHOE

MEMBER
2 POSTS

No I did not change either. I was going to leave everything else like it was and just take the shifter off.

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Tuesday, December 26th, 2017 AT 8:43 AM

WRENCHTECH

MECHANIC
20,758 POSTS

Unfortunately, we cannot give advice that results in disabling any safety feature. My advice would be to have a local mechanic install a clutch switch in place of the neutral switch.
Some further warning here is that you are trying to modify a computer controlled system. The computer monitors that neutral switch for certain things. Do not be surprised if you run into further issues like the computer activating a rev limiter because it does not know what gear you are in among other things.

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Tuesday, December 26th, 2017 AT 12:50 PM

GEORGE DONAHOE

MEMBER
2 POSTS

Thank you, I have the computer from the truck I got the five speed out of I did the same swap with my 1989 Chevrolet about ten years ago. A lot less computer stuff and electrical stuff on it.

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Tuesday, December 26th, 2017 AT 2:43 PM

WRENCHTECH

MECHANIC
20,758 POSTS

Yes, the 1989 is quite less complicated than the 1999. I sure do not understand why anyone would even attempt something like this. Why did you not just buy a manual if that is what you wanted? I used to do those swaps when I was a teenager on 1955-1957 Chevrolet's and even then it was a pain in the butt. I see no advantage to it now, even if the auto was fried. It is so much easier to just swap out a used one. I believe even the differential ratios are different for the auto.