Anybody know if replicated TOS is a clone of the OSS?

[DSteck]

I've got a 67 truck running a 2009 Corvette operating system with a T42 controlling a 4L80. The TCM functions as it should. The only problem I am running into is the speedo in the scanner reads about 4x higher than the truck is actually doing. The harness is from PSI Conversions, and the replicated TOS signal from the TCM is wired to C1 Pin 71 on the PCM. It responds to changes in vehicle speed... Just at a ridiculous level. The problem is its hitting the "speed limiter" and shutting the truck down at about 40-45mph.

I'll post the file in a bit. I'm just trying to see if anybody knows if the RepTOS signal is a true clone of the OSS or not. I'm thinking I may have to manually edit the PCM without the TCM connected to try and fix it, but I'm not sure.

Chris... HALP!!



Edit: Attached file. After thinking about this some more (sparked by thumbing through the GM Service Manual for a Corvette), I think we might be SOL. The Corvette is looking for a VSS signal from a sensor that is mounted after the mechanical adjustment of ratio by the differential. So 1000rpm output on the transmission gets dropped down to 292rpm from a 3.42 rear end. The 17 tooth reluctor would spit out about 83Hz at that trans output speed. An auto with a 40 tooth reluctor on the tailshaft at 1000rpm actual OSS is going to crap out 667Hz. Shit.

Chris, are there any calibration values for the RepTOS in the TCM? The only other option for the truck is to use the Chevy Express operating system in the PCM, but we want to avoid that because it's got a Corvette gas pedal.

[DSteck]

Fixed. Took some trickery of the VSS pulse. Since the PCM looks for a signal after the diff, but it's actually reading before the diff, you need to take the reluctor tooth count and multiply it by the diff ratio. For this vehicle, it has 4.10s and a 40 tooth reluctor on the output shaft, so the tooth count needed to be entered as 164.

[HartRod]

DSteck - are you using Dakota digital VHX gauges?

[HartRod]

bump

[DSteck]

No.

[HartRod]

Thanks. I'm using the VHX setup and just trying to figure out why I can't get a signal out of the harness. I get one from the BUS and on the scanner, but not when I connect the wire directly to the Dakota gauges. I was thinking it might be something in the tune, but haven't figured it out yet.

[DSteck]

The ECM itself should be able to spit out a vehicle speed signal.

[Shrek]

Gen IV Corvette E38 OS output a signal compatible with a pulse speedometer. Most Gen IV trucks communicate with the IPC (gage cluster) via serial data or CAN Bus. Most non-HD truck calibrations may be altered to output the Corvette style signal.

[HartRod]

The ECM itself should be able to spit out a vehicle speed signal.

Gen IV Corvette E38 OS output a signal compatible with a pulse speedometer. Most Gen IV trucks communicate with the IPC (gage cluster) via serial data or CAN Bus. Most non-HD truck calibrations may be altered to output the Corvette style signal.

Do you have to change any of these settings?

[Shrek]

What engine / transmission combination are you using ?

Post your tune when you have a chance ......

[HartRod]

6.2/6l80/tvs1900

[Shrek]

OK ... you are running a 2013 Camaro L99 & 6L80 tune ... the ECM OS is 12653674, which is common to Camaro, Corvette, and trucks. I have not used this OS in a Hot Rod build yet, but it should be able to output a usable speedometer signal - given that the Corvette requires this functionality.

Couple of things ... Output Source should be set to Serial (not RepTOS). What ECM pin location did you add the wire which you connected to the speedometer ?

[HartRod]

OK ... you are running a 2013 Camaro L99 & 6L80 tune ... the ECM OS is 12653674, which is common to Camaro, Corvette, and trucks. I have not used this OS in a Hot Rod build yet, but it should be able to output a usable speedometer signal - given that the Corvette requires this functionality.

Couple of things ... Output Source should be set to Serial (not RepTOS). What ECM pin location did you add the wire which you connected to the speedometer ?

I mechanically deleted the VVT and the AFM, so it is basically a LS3. It was orginally set to serial and still didn't work. I switched it to RepTOS just to see if anything changed (it didn't). It's a Speartech harness so I'll have to ask John which pin he pulled the input from (if I can't determine it myself). So all of the other settings, look good? What did you think about the tune in general?

[Shrek]

Unfortunately, I have neither the time nor the inclination to go through peoples tunes table by table ... I try to help people find their way around an impasse, such that they can tune from that point on their own.

As far as the settings in speedometer segment go, the original Camaro settings should work (to get an output), then the actual number of pulses may need to be altered to achieve an accurate speedometer display.

Best to check the continuity of the wiring harness yourself ... it is very easy to be out one pin / cavity / spot with the Molex connectors. Use a digital voltmeter with an audible alert ... set to continuity ... the speedometer wire should be on connector C1 (J1) of the E38.

[HartRod]

Unfortunately, I have neither the time nor the inclination to go through peoples tunes table by table ... I try to help people find their way around an impasse, such that they can tune from that point on their own.

As far as the settings in speedometer segment go, the original Camaro settings should work (to get an output), then the actual number of pulses may need to be altered to achieve an accurate speedometer display.

Best to check the continuity of the wiring harness yourself ... it is very easy to be out one pin / cavity / spot with the Molex connectors. Use a digital voltmeter with an audible alert ... set to continuity ... the speedometer wire should be on connector C1 (J1) of the E38.

Roger that. I will change it back to serial and recheck the wire for an output. I'm using this "schematic" for the pin out:

http://lt1swap.com/2010camaro_ecm_pinouts.htm


Also, I forgot to mention I'm not using a BIM, just the ECM & TCM if that matters.

[Shrek]

Too funny ... people may spend thousands of dollars on a project, yet often omit to spend a few dollars for OEM shop manuals.

These folks always seem to end up at Brendan's website. Unfortunate that he omitted to mention where to add the pin / wire for the speedometer output in the link that you posted.

[HartRod]

Too funny ... people may spend thousands of dollars on a project, yet often omit to spend a few dollars for OEM shop manuals.

These folks always seem to end up at Brendan's website. Unfortunate that he omitted to mention where to add the pin / wire for the speedometer output in the link that you posted.

OK, I give, . I thought on X1, pin 71 or 72, apparently not, lol.

[Shrek]

Those are the direct inputs from a manual transmission VSS.

ECM speedometer 4K output is C1 (X1 / J1) pin 57 ... which was not original used by the Camaro.

[HartRod]

Those are the direct inputs from a manual transmission VSS.

ECM speedometer 4K output is C1 (X1 / J1) pin 57 ... which was not original used by the Camaro.

I'll double check with Speartech and see if that is where his wire comes from. I'll update when I find out. Thanks for all of your help.

Rob

[HartRod]

Those are the direct inputs from a manual transmission VSS.

ECM speedometer 4K output is C1 (X1 / J1) pin 57 ... which was not original used by the Camaro.

OK, I did some checking today and I do have wire in pin 57. After verifying that, I did a continuity check and everything checked good. Now what?