akauto

hi, new guy here. just installed new crate motor, trans, and harness (from gm) in a 69 camaro, starts and runs, no codes, can read cam/crank sensor and rpm with scan tool, but no signal from bulkhead connector for tach or trans. it says its a low voltage 2 pulse/rev squre wave. with a meter, i have no wave form at all from either the bulkhead, or the ecm pin no (25 blue connector) what am i not getting? i think there will be a prize for the right answer. thanks for any help. hb

cam

iTrader: (9)

Most tachs require a pull up circuit in order to work properly. I used a 4K resistor 12v+ feed spliced into the tach circuit and it worked great for me.

MX6.0

Same here. 2.2K resistor

Grve66

iTrader: (3)

I had similar issue. I used the MSD 8913 box and it works perfect.

99VetteFRC

This is what I used on my Sun Pro Tach and had to set it for 4 cyl.

LS3R8

I had the same problem (posted an earlier thread) when trying to interface the Dakota Digital VHX with the ECU in my 67 Camaro. All we did to fix it was change the tach setting to "crank" in the tune and it worked fine. No need for a pull-up circuit. That was with the DD anyway - not sure if it works for other tachs.

regards

psiconversion

iTrader: (5)

LS3R8 suggestion will also work with an Autometer tach.

Jon
PSI

akauto

hi guys, i guess that i got a little technical with the whole problem, i wanted to see a signal out of the pcm, we tried all of our fancy test equipment to no avail. set tach to four cyl, installed resistor, and it worked. amazing what you can do to out-think yourself. thanks to all of you that persuaded me to follow the instructions. happy motoring. hb

cam

iTrader: (9)

Ha! Dude i chased a small wiring problem down for days and days I was CERTAIN it was tune related as the VATS patch was not sticking more than once per start up. Meaning the thing started and ran fine until i shut her down then it would only start on a handful of cylinders so I would flash VATS back off and it would run great again. So after teching myself and everyone else on the boards nuckin futz I finally poured over my wiring and voila found that one of the power feeds was hooked to bat instead of ign. Wired it up correctly and voila problem solved

Moral of the story? One never knows..... until you know

Glad you got it sorted.

Hart_Rod

iTrader: (3)

I used this thread to get the tach to work:


http://www.hptuners.com/forum/showth...ach-(autometer)

Does anyone know f something similar has to be done in order to make the speedo work? I've tried everything and still have not gotten it to work. Thanks,

Rob

cam

iTrader: (9)

The VSS pegging 158 is a common problem with these. Do you have the latest version of HPtuners? Signal set to Reptos or sumn like that?

Hart_Rod

iTrader: (3)

Actually mine isn't pegging, I'm not getting any signal at all, but I will try the RepTOS and see if anything changes. Thanks for the suggestion.

1989GTA

Me too and it also worked just fine.

Hart_Rod

iTrader: (3)

I used HPTuners to change the VSS o/p to "RepTOS", but I still don't get pulses when I try to program the speedo. Would you mine looking at a picture of my setup below and let me know if your's is similar or if I'm missing anything. Thanks,

1989GTA

Hart Rod if you are refering to my post I was only refering to the tachometer signal, not the VSS. I will be tapping into the GMLAN wires for the speedometer.

Hart_Rod

iTrader: (3)

No worries GTA. I was just tossing it out there for general consumption, LOL. My speedometer works when I use the OBDII Bim from Dakota Digital. However, I was just trying to hardwire it also, so when I am running the HPT scanner, I would have the speedo on my gauges and not have to look away from the road at the scanner. Just trying to be safe while I'm tuning. The tach works great, so I guess I should be happy with that, .

fieroguru

iTrader: (1)

I have an E67 running an LS4 in an 88 Fiero using the stock GM Tach and Speedo. To make the tach work, I used this stepper circuit coming off C1 (Blue) pin 25 and set the tach output to "Crank":


To make the speedo work, I used this circuit coming off C1 (Blue) pin 39 and set the speedo output to "Serial"

Hart_Rod

iTrader: (3)

Here's the answer to the Speedo problem:

Chris - I downloaded the new version of HPTuners and made the changes - you da man!!! The speedo now works correctly!!! Thanks again,

Rob