ĦMR.AWESOME!

iTrader: (2)

I got some problems with my car so I was testing the resistance of the CTS and while I was at it I was doing some trouble shooting with my radiator fan. I went to start the car to do some more testing with the rad fan but it wouldn't start. i had forgotten to reconnect the CTS. Anyway, just for fun I checked the codes and I got a 22, 34 and 42. Those all say low voltage to different sensors. Is that supposed to happen? It seems weird that none of the codes had to do with the CTS. I cleared the codes and recreated the conditions to make sure those weren't old codes. Anyone willing to do the same thing to see what happens?

Oh another weird thing. One of the problems with my car is that while it's idling, it acts like it's gonna die and then revs up to catch itself. It repeats that process for awhile. If I drive it and it warms up it usually doesn't do that, but sometimes it still does even after it's warm. After I reconnected the CTS and cleared the codes, I started the car and it wasn't feigning death anymore. It was idling just as it's supposed to. I haven't started it up today so i dunno if it's "fixed."

But my main question is this: with the CTS disconnected should I be getting codes 22, 34 and 42?

ASE doc

Code 42 is not a low voltage code. It is an EST circuit problem. Shared low or high voltage codes on multiple sensors isnt that uncommon. Low voltage codes are often caused by loss of 5v referrence power, generally a bad connection at the ECM, this can affect several sensors at once.

Code 42 can be caused by several things. Although since the EST is bypassed by a 5v signal when cranking, I expect that this code was also caused by loss of referrence voltage. That would also explain the no start. Did you have the CTS connector jumpered when you tried to start the car? You may have pulled referrence low this way.

Be sure that your CTS connector is in good shape also. The sudden cure of your trouble makes me wonder if you have a bad connection there.

Damon

Trying to start a warm engine with the CTS disconnected is futility. It thinks the engine is -40*F (bottom of the range) and it floods out very quickly.

And the ECM won't immediately know that the CTS is disconnected. It's gotta run the engine a while with the expectation that the temp will rise. If it doesn't after some specified period, it might throw a penalty flag. But until it figures that out it takes the reading as correct and runs the engine accordingly (badly).

ĦMR.AWESOME!

iTrader: (2)

Thanks for the replies. Yea, I know that the car won't start without the CTS connected. I simply forgot to reconnect and tried to start it. The thing that piqued my interest was that those three codes were set by trying to start the car without the CTS connected. I thought it a bit odd that not having the CTS connected would cause that.

So ASE, do you think there is another problem that is causing the TPS, MAP and EST sensors/circuit to get too low of a voltage when the CTS isn't connected? And why would the codes be set only when the CTS is not connected? I will check the connector out tomorrow.

Thanks for the help guys.

ASE doc

The one common cause for a low voltage code on those three senors is the 5v ref circuit from the ECM. Anything that might pull that down, such as a short to ground.