Does anyone know what wire (the tach wire coming out of the pcm) is on a 09 5.3 gmc sierra, say the wire for hooking up a window switch for nitrous I have tried some of the local dealerships and the parts dept is clueless.
Does anyone know what wire (the tach wire coming out of the pcm) is on a 09 5.3 gmc sierra, say the wire for hooking up a window switch for nitrous I have tried some of the local dealerships and the parts dept is clueless.
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E38? Pin 48 on J1.Originally Posted by Tunning @ LMR
I'd also like to know the answer to this question. I think the ecm pinouts on this should be the same as my 2007 right? Which pin has the signal to the tach? I would like to add a tack to my project and haven't found where to connect one?
Same on most E38's. G8 is one exception. Some trucks too. GM uses a number of different configs for the tacho signal source/destination.
I will try and help but the new gmt900 trucks have like 10+ rpo codes for engines so the last 8 of the vin or the rpo code would help.
I might be incorrect but I think that on the 900 trucks most of the ipc "instrument panel cluster" inputs are done over "gm Lan" or logic
So there is no one wire I think
Instrument Cluster Description and Operation
"Tachometer
The IPC displays the engine speed as determined by the ECM. The IPC receives a serial data message from the ECM indicating the engine speed. The tachometer will default to 0 RPM if:
• The ECM detects a malfunction in the engine speed sensor circuit.
• The IPC detects a loss of serial data communications with the ECM. "
Dustin
HI Dustin! I came to a similar conclusion looking at the schematics that the tachomter signal was probably generated in the IPC where the factory tach resides. This doesn't help me since I'm not using a factory Instrument panel
If there is no wire in pin 48 on the ECM, a wire can be added and HPT used to recalibrate the tacho feed from serial to crank. When on "crank" normally a tach signal is sent out of pin 48. To qualify that: this works on G8 setups. And yes the dash IP readouts: tach/speedo/fuel level/temp are sent via the CAN through the BCM and then low speed bus to the IP.
I have the same issue and is not the pin48 on J1
any one can help??
It is on pin 48 but its disabled in the PCM and must be ebabled for it to work.
Set tach type as "crank" and 15/15 for the periods. You will more than likely also need a pull up resistor for your aftermarket crank
I am running into the same problem with my 2008 LY6. I have repinned a wire to pin 48. In HP tuners I have flashed it to "crank" and 15/15. Using a variety of resistors for a pull up signal around 1K and a switched 12volt wire I get nothing. I have tried the high and low periods as 4/4 6/6 3/3 and nothing changes. Is there a simple way to see if I am getting a crank signal out of pin 48?
Is there anyway to get a tach signal somewhere else?
I think this is like a double post...I just replied in one but I thought it was for a remote start sys, but maybe the same thing applies, just pull the signal from one of the coil pack wires.
I was wondering if one could pull a signal off the coil packs. I think I read a few post about this causing problems but it may be the only thing I can do in this case. Anyone else running the tach off the coils with a Gen IV engine?
As a follow up, I got my tach to work off pin 48 on my e38 ecu. The wire I added from pin 48 had a break in it and I was not getting signal. I set my tach to "crank" and 15/15 for the high low period. I added a 1k ohm resistor and a 12v switched input for the pull up circuit. Tach now works properly.
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