I just installed a pcm from a 98 ram into my 97 ram. Now my tachometer doesn't work. The "new" pcm solved some driveabilty problems I was having;so I'd like to keep it. I hate not having a tachometer, though.

Can I wire around the pcm?

What do you guys think?

Thanks,
Kevin

 

The problem is in the new PCM. PCM's are generally not interchangeable from year to year. The only thing you can do to get the tach back is to re-install a 97 PCM.

What performance issues were you encountering that caused you to attempt this?

 

The reference voltage to some of my sensors was low. I think my pcm got some moisture inside. It mainly affects the transmission shifting and Air Conditioning.

I know that some will say the pcm has nothing to do with transmission shifting. The transmission shifts when line pressure rises above governer pressure (or vise-versa). So, if the reference voltage to the governer pressure sensor is incorrect, it does have a minor effect on shift quality. I can best describe it as "hunting" for the right gear under certian light throttle situations.

The A/C just randomly quits. Everything check out O.K. with the system.I forget how I figured out that it might be computer related. That was last summer.

I was hoping I could by-pass the computer for the tach.

 

If you can't find the 97 PCM locally, check www.car-parts.com
I have had a lot of luck finding used parts for reasonable prices on that site. Most of them local to me.

Wish I could help you more.

 

u could bypass it and install an aftermarket tach.. should run off adistributer or injector wire.