Jody at Corvette C4 Replacement Gauge Packages, Corvette C3 Replacement Gauge Packages, Corvette C3 and C4 LSx Rapla is building a 4' ETC cable with the proper connectors for my LS7 and I wanted to pass on the info: Cost: $65 plus shipping, time: should be sent out next week. Probably more cable than needed but rather too long than too short, eh?
ETC extension cable
- Thread starter CANTDRIVE55
- Start date
Well, I probably had the terminology wrong as this extends to the pedal assembly from the GMPP engine harness. I want plenty of cable to get it far from the front dress of the engine. I broke down the harness and didn't seem to get enough cable to be comfortable. I didn't want to splice/solder. Each build is slightly different so my wiring layout is probably as unique as everyone else. I know Cam got his DBW cable to stretch to the pedal assembly.
Good call on not lengthening it by splicing - everything I've read seems to indicate this is a very bad idea.
I'm just surprised people are having issues with not having enough length on it - I've got mine mounted on the passenger firewall, and heading straight down, then towards the driver side, through the gas tank, and to the pedal assembly, I need to loop it, underneath the driver seat, in order to remove all the slack.
I'm just surprised people are having issues with not having enough length on it - I've got mine mounted on the passenger firewall, and heading straight down, then towards the driver side, through the gas tank, and to the pedal assembly, I need to loop it, underneath the driver seat, in order to remove all the slack.
Ken Roberts
Supporter
The pros will tell you not to lengthen them by splicing but only for liability reasons. They don't want to be held liable if you screw up on the wiring order or quality of soldering. The GMPP engine harness instructions also has a disclaimer.
If you are confident in your soldering ability and use shrink tubing then you have nothing to worry about. The extension harness sold by various vendors are no different then extending the harness by soldering. I'd even bet the signal transmission would be superior by soldering rather then a male and female pin touching each other and which corrode over time.
If you are confident in your soldering ability and use shrink tubing then you have nothing to worry about. The extension harness sold by various vendors are no different then extending the harness by soldering. I'd even bet the signal transmission would be superior by soldering rather then a male and female pin touching each other and which corrode over time.
I thought it also had to do with the length of the wires and resistances and not being able to read it properly? It's been a while, but I could have sworn that the problems with extending it went beyond a simple bad joint or messing up the harness wires.
Ken Roberts
Supporter
Then the extension harnesses sold by the vendors would suffer from the same problems!
Maybe it works if the wires are exactly the same length? I don't know enough to do more than guess, but I have read about people having problems after splicing the DBW, and, if you open up the harness, there should be more than enough wire to get to the front of the car (unless you put the fuse box at the very back of the car)
I bought an extension from a place in FL that says they make them all the time with no problems. When I asked if 4 feet was too long, he laughed and said they made 10' ones for the sand rail crowd all the time.
Presumably the added length of the cable and the resistance of the connectors doesn't change the resistance of the overall circuit in a manner that has an effect on the ECM.
Presumably the added length of the cable and the resistance of the connectors doesn't change the resistance of the overall circuit in a manner that has an effect on the ECM.
I think it really depends on the harness. I bought a C6 Corvette LS-2 Harness from GMPP. The DBW cable was short by about 1.5 feet. Others bought harnesses from other sourcess and the DBW cable was much longer than needed. It could be the difference between a harness that was intended for a Corvette, Camaro, Cadillac CTS-V, or generic crate engine.
And to your earlier point, I was also told by one of the techs at GMPP, that if a longer DBW cable has to be spliced into the harness, you need to make sure that the wires are as close to equal length as possible. Because they do opperate by reading resistance. And different wire lengths will yield different resistance levels, and in effect be read differently by the ECU. There is a +/- tolerance built into the programming to read the signal. So if the resistance levels are outside of that tolerance, the ECU will not process the signal correctly.
At least that's how it was explained to me.
With that said...
I bought an extension connector with a 18" pigtail from StreetRod Headquarters (I think it was), and was able to splice it into the harness. It was soldered and shrink tubed, and it works fine. Great throttle response, and no hick-ups at all during Dyno Tuning.
For what it's worth...
Mike
That doesn't make sense to me. I don't have direct experience of this sensor, but I can do maths
:The resistance of the potentiometer is around 5kOhm (from here), whereas 6m / 20' of 20AWG (I'm guessing the gauge) has a resistance of about 0.2Ohm, so equivalent to 0.004% of the throttle travel. You won't be able to detect that.
There will also be very little current; we'll basically see 1mA (5V / 5KOhm). That will produce a voltage drop 0.2mV. Again, this isn't going to measurable, especially in the electrically noisy environment of a car.
Then there's the resistance of the potentiometer internal connection and the connectors. I haven't seen good information for this, but I've seen numbers around 10mOhm (example here). Again, not significant.
In conclusion, I don't think that adding wire and good quality connectors will affect the ECU's measurements measurably. That matches with people's experience. There is the increased number of points of failure though, but new car electrics (when clean) seem fairly reliable IMO.
