420A 2gNT tach not working

[Tucker3500]

The tach just stopped working for me in my 1997 eclipse gs 5 speed I have a check engine light and it flashes sometimes then stays solid but it runs fine no smoke and it does not appear to be missing any I have just changed the plugs to ngks iridium I am wandering if the tach and the light are related or separate and any possible fixes to my problem any help would be greatly appreciated thank you

 

[gst-turbo]

Have u checked fuses

 

[EC17PSE]

Have you checked the speedo drive on the gearbox? Is it broken or cracked? Check that out

 

[Tucker3500]

I have checked all the fuses they are all soon the speedometer is still working so I don't that link it the speed sensor unless that how it senses the rpm to or does any one know where it reads the rpms

 

[EC17PSE]

rpm is based from a few locations, can be crank, transister, cas, depends what side your going to look at. Some are ecu based and some are mechanical based. Try testing the power transister,

Then try the ecu pinouts at #54,58/4/88/89 they are ones to try out as they all go through there but as i said some are just for the ecu to read and some are to tell its fired but it could be related and gives you a good start

 

[luv2rallye]

2g tach signal is only from power transistor.

 

[EC17PSE]

^^^^^ listen to Gary. He knows alot me on electronics then i do. He will help you through this

 

[luv2rallye]

I'm sorry, I didn't realize you had the non-turbo. On the 2g NT the tach signal is from the PCM.

 

[Tucker3500]

rpm is based from a few locations, can be crank, transister, cas, depends what side your going to look at. Some are ecu based and some are mechanical based. Try testing the power transister,

Then try the ecu pinouts at #54,58/4/88/89 they are ones to try out as they all go through there but as i said some are just for the ecu to read and some are to tell its fired but it could be related and gives you a good start

So today I came out started it up and the tach was working but I still have check engine light so I'm guessing the problem is intermittent or it was a loose connection