99 2 door 4x4. LS2 swap. Cruise Control/Tach not working

[ls2hoe]

So when i went into this whole swap I wasn't really sure on what to expect other than more power, reliability, shock factor. Some things I'm not technically savvy about and I sure someone here can point me in the right direction.

My cruise control doesn't work as of now the shop its at doing some fine tuning will not attempt to make it work. My swap is Drive By Wire with the original computer still running for gauges lights etc. Does anyone know what needs to be done to have cruise control working properly?

Also my tach doesn't work. The shop said you have a rev limiter theres no need to have a tach, however i disagree, I want my tach so if anyone knows how to remedy this as well I would really appreciate any feed back.

 

[livingez_123]

Not sure if the tach output from the new ECM will be compatible with your old gauges. I guess you can try. Find the pin# for the tach signal on your new ECM and find the tach output from your old ECM, cut and attach the new wire from the new ECM to your old tach lead. Wil this work? I don't know.

As far as your cruise goes, it should be a matter of connecting the right wires from your cruise switches to the proper inputs on the new ECM. Again will this work? what do you have to lose in trying.

 

[mcm1209]

So when i went into this whole swap I wasn't really sure on what to expect other than more power, reliability, shock factor. Some things I'm not technically savvy about and I sure someone here can point me in the right direction.

My cruise control doesn't work as of now the shop its at doing some fine tuning will not attempt to make it work. My swap is Drive By Wire with the original computer still running for gauges lights etc. Does anyone know what needs to be done to have cruise control working properly?

Also my tach doesn't work. The shop said you have a rev limiter theres no need to have a tach, however i disagree, I want my tach so if anyone knows how to remedy this as well I would really appreciate any feed back.

If the shop is telling you you don't need it, when you want it! They would not get to much of my business. Why cant they say "we don't know how to make it work"?

If its drive by wire then it has to come from the PCM. The PCM tells the TB when to open and close. On our style trucks, we have a physical box that holds the throttle open for cruise. Its the box by the brake booster on the fire wall.

For the tach, im pretty sure I read somewhere, that you have to find the tach wire on the LS2 harness and tap it to the tach wire on the old harness. But i could be wrong.

 

[ls2hoe]

If the shop is telling you you don't need it, when you want it! They would not get to much of my business. Why cant they say "we don't know how to make it work"?

If its drive by wire then it has to come from the PCM. The PCM tells the TB when to open and close. On our style trucks, we have a physical box that holds the throttle open for cruise. Its the box by the brake booster on the fire wall.

For the tach, im pretty sure I read somewhere, that you have to find the tach wire on the LS2 harness and tap it to the tach wire on the old harness. But i could be wrong.

yea I agree with you but its user warranty there so i was having a few extra goodies done with they were fixing some minor issues.

My new set up is all drive by wire so there aren't any cables or the cruise box it all comes from a signal from the ecm

---------- Post added at 10:00 AM ---------- Previous post was at 09:57 AM ----------

Not sure if the tach output from the new ECM will be compatible with your old gauges. I guess you can try. Find the pin# for the tach signal on your new ECM and find the tach output from your old ECM, cut and attach the new wire from the new ECM to your old tach lead. Wil this work? I don't know.

As far as your cruise goes, it should be a matter of connecting the right wires from your cruise switches to the proper inputs on the new ECM. Again will this work? what do you have to lose in trying.

you're right just something about splicing wires to do with the ecm worries me lol

 

[SunlitComet]

the tach fed of fthe coil on the vortec 350 and red the signal as an 8cyl mode. you will need to tap new coil and find a way to convert that one coil pulse to give 8 that the tach would respond to. as for the cruise it needs vehicle speed info from the old pcm which is one reason the old pcm and sensors are retained.