iamsuperbleeder

So this is a LONG shot, but I've tried to register on TWO DIFFERENT S10 forums and I can't get EITHER of them to send me an email to activate my account, sooooo, I'm asking you guys here

Technically is a 95 GMC Sonoma I'm working with (dad's truck), but same thing. It's a 2.2 4cyl 5 speed manual, nothing special at all. But being a manual, sometimes having a tach is nice. It didn't have one originally, so I did a little research and everything I found said that you could drop a 95-97 cluster in it with a tach and it should be prewired and it should work. 4cyl and V6 tachs are not going to read the same, but that's easily fixable with playing with capacitors from what I also dug up.

So I got ahold of a cluster with a tach, put it in, and low and behold everything works fine, accept for the tach...

Anyone have any experience with this? The shift light works, not sure if that's activated by the ECU or directly from the tach signal; I would assume the ECU because it has to take in throttle position and speed as well as tach to calculate engine load and trigger the light at the right time, but the fact that the light does function tells me that there's a tach signal going from the coil to the ECU at least. At least that sounds right to me What's the chance I got a cluster with a faulty tach stepper motor? Not sure how often they go out, if it's anything like the early 2000's full size GM clusters, I know those go out a LOT lol. This cluster is out of a 97 Blazer so I wouldn't put it past being just old and not functioning like it should.

I guess my best plan of attack to find out if the cluster is at fault is to just probe the tach signal wire that goes into the cluster while the engine is running?


Thanks for any input

BigBluePile

iTrader: (3)

We work on Toyota here pal......except DC.....not sure what he actually works on....

iamsuperbleeder

not in this section we don't!

BigBluePile

iTrader: (3)

I'm telling the staff on you.....

RobotMoose

iTrader: (1)

I think the ECU might generate the tach signal, and maybe the later cluster doesn't like the earlier ECU's signal.
As a test, maybe run a length of wire directly from the coil to your tach and see if you can get it to work.