Hey guy i have a 85 iroc with a 350 swap and a Qjet , i keep getting a code 15. I will start the car drive it for about 15-20min and then it will come on , i replaced the sensor and plug still didnt help. I also check it with a multimeter, and got 5v from the yellow wire with the meter grounded to the car. The car stumbles at idle and , i checked the timing and it says im getting 40* base with the spark thing unpluged and at idle , if anyone can help let me know i need to get the car smogged and i know it wont pass the way it is.

Thanks,chris

 

The likely problem is that the CTS circuit is open (no connection between the CTS and ECM or CTS black wire and ground). There may also be a problem with the CTS itself. The resistance of the sensor shoudl be as follows:

 

If you replaced the CTS sensor (the one on the intake manifold- the one in the side of the driver's cylinder head just runs the dash gage) and it tests OK, then you're down to wiring and the ECM.

I had a weird one on my 91 Blazer a while back- kept throwing either a 14 or 15 - I forget which. Turns out the sharp edge of one of the engine brackets had worn through the plastic wire conduit, into one of the CTS wires and from time to time it would throw the code- only wile accelerating (as the engine torqued over), never while standing still. I traced the wires back and found the culprit, but only after I had replaced both the CTS and the ECM.

 

thanks guys ill try and check over the wiring tomorrow and ill try to clean the ecm plug to ill let you know if it helps

 

I have the exact same Code 15 problem, except for the idle stumbling and timing problems. I verified that the CTS was getting 5V, replaced the CTS with a new one, and it still gives me the code 15 after 10-15 minutes of driving. The plug that goes to the CTS was repllaced at some point and its wires were spliced with the original wiresgoing to the ECM. It it has those crimp connectors. Since it gives me 5V I dont see why it would be a problem, but im going to try to remove thosecrimp connectors and solder/heatshrink the wires together to see if that helps.