Results 1 to 5 of 5

Thread: Why no tach options for LQ9 from 04 Escalade?

  1. #1
    Potential Tuner
    Join Date
    Jan 2021
    Location
    Wisconsin
    Posts
    9

    Why no tach options for LQ9 from 04 Escalade?

    I've put an LQ9 LS 6.0 in my 99 S10 and I'm using the 6243 PCM that has been programmed for the LQ9. Everywhere I read about getting the 99 S10 tach to work the posts say to set the tach output with HPTuners to CRANK and 3/3. I get the 3/3 part, but the only choices I'm offered for tach type is 12V pullup or no pullup. Where do I find the choices between frequency and crank?
    I understand the signal from the pcm may be too weak for the tach and I'll need to add 12v and a resistor, but that's a different issue.

  2. #2
    Advanced Tuner Shrek's Avatar
    Join Date
    Nov 2011
    Posts
    753
    Quote Originally Posted by oldeerslayer View Post
    I've put an LQ9 LS 6.0 in my 99 S10 and I'm using the 6243 PCM that has been programmed for the LQ9. Everywhere I read about getting the 99 S10 tach to work the posts say to set the tach output with HPTuners to CRANK and 3/3. I get the 3/3 part, but the only choices I'm offered for tach type is 12V pullup or no pullup. Where do I find the choices between frequency and crank?
    I understand the signal from the pcm may be too weak for the tach and I'll need to add 12v and a resistor, but that's a different issue.

    You are mixing Tach information for a Gen 3 PCM (P01 or P59), with Tach information for the later Gen 4 ECM (E38 or E67).

    The later Gen 4 ECMs have a configurable Tach output type - CanBus, PWM, or Crank.

    Your controller is a Gen 3 (24x) PCM (P59).

    Your Gen 3 PCM (P59) does not feature a configurable Tach out type - hence why you don't this in the available Tach parameters.

  3. #3
    Potential Tuner
    Join Date
    Jan 2021
    Location
    Wisconsin
    Posts
    9
    Thank you. The 6243 is a late (04) P59 so I guess I'm screwed as far as getting my 6 cylinder tach to work with the V8. Or will just setting it to 3/3 do it. Plus the 12V pullup if needed?

  4. #4
    Advanced Tuner Shrek's Avatar
    Join Date
    Nov 2011
    Posts
    753
    It is important to try and understand the information that you have read, rather than just regurgitating it.

    External Tach "pull-up" circuit ...

    The Gen 3 P01 PCMs (1999 - 2002) rarely require an external Tach pull-up circuit to be added.

    The Gen 3 P59 PCMs (2003 - 2006) often require an external Tach pull-up circuit to be added.


    Gen 3 PCM (P01 or P59) Tach High / Low pulses ...

    The OEM Tach settings for a Gen 3 V8 LS engine are typically 6 High pulses and 6 Low pulses. This equates to a traditional 4 cylinder Tach configuration.

    Changing this to 3 High pulses and 3 Low pulses - equates to a traditional 8 cylinder Tach configuration.

    What Tach settings your conversion may require - using an OEM cluster - will be a matter of experimentation. Some OEM clusters integrate well with an LS conversion, others do not.

  5. #5
    Potential Tuner
    Join Date
    Jan 2021
    Location
    Wisconsin
    Posts
    9
    Thanks for the additional info. Seems we agree, I'll be using an 04 P59 PCM, the same one used in 04 S10's and vans. With the 4.3 in the S10 and 5.3 and 6.0 in Express vans. I had to go with this particular one so I could use a 12V A/C request. Other P59's don't necessarily accept a 12V request. Probably should have used an 0411, but since I'm DBW with the Escalade 6.0 I thought I'd stick with the blue/green PCM.
    The plan is to try 3/3 or 6/6 w/o pull-up and if that doesn't work either way I'll add the pull-up. If that doesn't work I've got a couple old Sun external tachs laying around from back in the day. I'll probably need to ask again how to wire those if it comes down to it.