patooyee

iTrader: (1)

I've got an LS2 out of an '05 SSR in an off-road buggy I'm building. I'm wiring it up and I have the ECM all powered up and running (vehicle isn't running yet though). I'm using a DBW pedal out of the same year Corvette. Neither the SSR or 'Vette use a TAC module. The circuit numbers and wire colors are all the same, just the positions within the connector are different from the SSR application to the Corvette pedal. I've wired it so that the circuit numbers coming out of the pedal exactly match the circuit numbers going into the ECM. The wiring diagrams match exactly at that point between the two vehicles right down to the connector positions at the ECM. (Both use e40 ECM.)

When I power up the ECM it flutters the throttle plate just a tad. Then when I press the gas pedal nothing happens unless I floor it at which point the throttle plate flutters briefly again and sets a P2138 code. (DTC P2138 Accelerator Pedal Position (APP) Sensor 1-2 Correlation) From that point forward it won't do anything no matter what I do to the pedal until I clear the code, at which point I can duplicate the issue exactly.

Obviously the pots in the pedal aren't jiving but I find it hard to believe there is anything wrong with it as it is a new pedal straight from GM. The motor was pulled from a wrecked SSR with 23,000 miles on it. Anyone got any advice?

J. J.

rsz288

ECM from SSR pedal from vette?

patooyee

iTrader: (1)

Correct. Everything is from the ssr except the pedal.

J. J.

rsz288

Would recommend an SSR pedal. If the diagram showed the pedal wiring as different there was a good reason for it.

patooyee

iTrader: (1)

Thank you for the valuable input. Maybe I should have left the engine in its original vehicle since the wiring diagram between it and my buggy is drastically different also then? Maybe everyone alla round the world should stop swapping these engines since the wiring diagrams don't match up?

I'm not the first to use a pedal from a different application. The diagram is EXACTLY the same between the 2 vehicle with the exception of the pin out at the pedal plug. Does anyone else have any suggestions?

J. J.

FastKat

iTrader: (10)

Agreed. You want to have the ECM, throttle body and pedal all from the same year/make/model car.

patooyee

iTrader: (1)

It is my understanding that the two potentiometers in the pedal sweep 05 v and 5-0 v as the pedal is pressed. The two in the TB sweep opposite which the ECM interprets and then uses to actuate the two TAC motors. It is also my understanding that ALL the pots in ALL the GM pedals sweep the same voltage reference signal. Given this, it seems to me that any pedal should work in any application if wired correctly. Can anyone explain to me why that wouldn't be?

J. J.

garys 68

iTrader: (1)

Check to make sure you have good voltage. Low volts will cause the TB to flutter, throw a code, go into limp.
A gunked up TB can also cause a flutter and throw a code.
Other than that, probably the wiring. GM seems to use some black magic when it comes to DBW.

patooyee

iTrader: (1)

Thank you. TB is clean. Voltage is higher than I've seen lots of vehicles with bad alternators that can drive down the road have.

J. J.

FastKat

iTrader: (10)

There are a couple threads on here that detail the specific differences between pedals. Finding those threads might shed some light on your problem.

Have you bench tested the pedal to make sure both potentiometer circuits are functioning properly? Try that, and make sure both pot circuits have the same output (as each other) for several different pedal positions, including both at 0% and 100% throttle. If there's a problem there, I bet you'll pick it up pretty quickly. You'll also know for sure which terminals are your +5V, GND, and output signal, which means you'll be able to be absolutely certain you're giving the '05 SSR ECM exactly what it wants to see as per your SSR wiring diagram.

patooyee

iTrader: (1)

Thank you. I did search and found a little info. My diagrams look almost identical to the ones in this thread where he says what I am doing should work:

https://ls1tech.com/forums/conversio...-corvette.html

There was a little info in this one too:

https://ls1tech.com/forums/generatio...al-donors.html

But I still have yet to find anything definitive. Maybe you know of another thread that I missed?

J. J.

patooyee

iTrader: (1)

Ah ha! According to Alldata, it would seem that ya'll are correct and I am incorrect on the voltage sweep:

SSR:
"The APP sensors are used to determine the pedal angle. The engine control module (ECM) provides each APP sensor a 5-volt reference circuit and a low reference circuit. The APP sensors provide the ECM with signal voltage proportional to the pedal movement. The APP sensor 1 signal voltage at rest position is less than 1 volt and increases as the pedal is actuated. The APP sensor 2 signal voltage at rest position above 4 volts and decreases as the pedal is actuated."

Corvette:
"The APP sensors are used to determine the pedal angle. The ECM provides each APP sensor a 5-volt reference circuit and a low reference circuit. The APP sensors provide the ECM with signal voltage proportional to the pedal movement. The APP sensor 1 signal voltage at rest position is less than 1 volt and increases to above 2.5 volts as the pedal is actuated. The APP sensor 2 signal voltage at rest position is near the 4 volts and decreases to less than 1 volt as the pedal is actuated."

So I need to find a 5-volt sweep pedal with the correct plug. Thank you.

J. J.

FastKat

iTrader: (10)

Wow, that is a really subtle difference. I wonder if the difference between the two pedals is real, or if one Alldata description is simply more detailed than the other.

Good luck with it either way.

patooyee

iTrader: (1)

The voltage difference is real. I've confirmed the two different types via other threads on this board. In addition, it perfectly explains the error code. I've also hooked up my VCM Scanner and read the outputs of both pedal sensors and sensor 1 reads about half of sensor 2 which makes sense and further explains the error code.

J. J.

rsz288

You have pretty well got to the bottom of it. GM uses several different APP curves for each of the two APP sensors. There are parallel 0.5-4.5V, there are inverse 0.5 - 4.5V, (approx voltages) there is another one which I cant recall on earlier TAC's, and there is the G8 type also used on some trucks which uses inverse curves with slightly different end points.

patooyee

iTrader: (1)

So for some reason very few parts houses list an APP sensor under any variation of the name for a 2005 SSR. You can't even find any on eBay. BUT, according to Alldata, a Trailblazer pedal from the same year features the same voltage sweeps, connector, and connector pin-out. In addition, it has the same photo and part number on rockauto.com (the only parts houses that has a listing for it) and they are plentiful and cheap on eBay. Would everyone here say that it is a safe bet that the Trailblazer pedal will work for me?

J. J.

FastKat

iTrader: (10)

Is it for the V8 Trailblazer SS (TBSS) or all the Trailblazers?

It sounds like you have a good match, especially based on rockauto. However, it might be worth checking out on gmpartsdirect.com - pull up the SSR pedal and the Trailblazer pedal and make sure they're the same part number. If GM uses the same part number, you have a winner!

patooyee

iTrader: (1)

So far every Trailblazer I have checked for 2005, including all engine models (V6 + V8). Gmpartsdirect.com does not have a listing for it on the SSR and I have emailed them countless times over the past year trying to deal with this issue and they haven't returned a single ******* email. I hate those people and prefer not to do business with them anyway. Their service is the worst in the industry. Their only saving grace is their pricing.

J. J.

85MikeTPI

iTrader: (9)

GM P/n for a SSR pedal assembly is 15145758 if that's what you're looking for.

Just checked, same as the TBSS pedal 15145758

patooyee

iTrader: (1)

Thank you. That does confirm it.

J. J.