I have an 89 IROC originally LO3 305 TBI. I have swapped in an 03 6.0 LQ9. I have my tach connected to PCM C2 (green) pin 10 (white); it’s labeled as Engine Speed Signal. But I’m not getting anything on my tach. It will jump when I turn the key on but nothing after that. The tach was working before so I don’t think that it's bad. I have done a lot of research and searching and this is how I understood that it needed to be connected. Am I missing something?
Thanks,
Ryan

 

You need an adapter box alla Baker electronics to convert the signal to 4cyl pulse. If you already have that and still no worky take a look at the thread below titled "LS1 tach issues"

 

Ok, here is what I did if anyone has this problem in the future. Evidently the newer truck PCM's are a little different so you need a 5000 ohm pull up resistor between a 12 volt ignition line and the tach signal wire. Speartech answered this for me; here is a link to the thread on LS1tech.

 

What did you do for the cable drive speedo and the vss?

 

good info and I belive efilive has a switch in the setting for this called "tacho pullup enable"

and here is there discription

If Enabled, the Tacho Output will have the PCM's internal 12V pullup applied to the output signal.
If using an aftermarket Tacho please check with the manufacturer if this would be required.

Only the following values may be entered into this table:
- No
- Yes

 

I still dont have my cable driven speedo working yet. I'm using a t-56 for my tranny so the VSS plugs directly into that. The only option for the speedo that I have been able to find is the converter box that Hawks resales. I dont really want to use that converter box, so for the meantime I will be using a ScanGauge.


I don't have any tuning software yet. I used wait4meperformance.com to tune the PCM for me. I was talking to them a few days before I started this thread and I was told "you need to buy a LS1 converter box because the IROC tach isn't compatible with the LS1 engine". That didn't sound right, I feel that they were just trying to get me off their back. I don't like the mail tune because I don't know how anything is setup in the PCM.

 

you know I really did not want to buy the program but I figured after having stuff changed twice (no tune just changing simple things) it would have payed for it's self anyway.

If tunercat would not have sold there ls1 edit stuff to jet not only would have it been cheaper something like 375.00 I hear but I really like TC and the support is top notch.


of course the ideal way was the old free edit stuff that was out several years back. from what I am told people where using this and charging people for tunes which of course pissed the nice guys off and they said no more.

glad to see you have a great cheap/free fix and this should help many more people.. thanks for sharing!