3-wire CTS

[caffeine]

I know that a lot of 3500 conversions in originaly iron head/Gen II cars use a 3-wire CTS that has been turned down to M10x1.5, they purchase an adapter, or drill/tap their head to 3/8" NPT.

I'm just wondering if anyone has simply tried using a 98 Camaro LS1 3-wire sensor?? It already has M10x1.5 threads.

[1988GTU]

I ran across that with a replacement cts for an ls motor not long after my swap and forgot all about that! Good that you posted bout it.

[3400-95-Modified]

HOT DAMN! That's good to know!

[Superdave]

good find!

I remember discussing this years ago but I had already drilled/tapped my LIM for the bigger sensor. I tried one that was turned down but it was too thin and broke eventually.

[shapeshaver]

Would the voltage supply and range be what the computer expects to see? I'm new to the wonderful world of automotive electronics, but in the industrial controls word there are commonly 3.3V, 5V, and 12V voltages that can be used and expected by the controller. Are all Car sensors running straight from ~12V supply? Does the sensor get 12V battery voltage supplied to it and scale the output to the computer over a defined range? And, are the OBD1 ECM's circuits all 12V and not TTL?

[caffeine]

GM sensors are usually pretty consistent when it comes to signal. I can't remember though if the gauge signal and ECM signals are the same though.

[88corsica5spd28]

I believe the CTS (and other resistance based sensors) are given a 5v reference signal.

[Superdave]

Yep, 5V. A-D conversion is done on the ECM (I forget the specifics on the '7730) then the values are used in the calculations.

Pretty much all GM sensors have the same resistance VS temperature curve.

[robertisaar]

pulled up to 5V via a 348 or (combined) 4K impedance, depending on the range being sensed and the sensor is used as the second part of a voltage divider. the raw A/D values get used for 2D normalization lookup tables and then you have the nice and easy X*1.35-40 for temp in *F.

guage sender and ECM's sensor resistance curves seem to be just slightly different enough to not be able to use them reliably.