Code 15
Thread Starter
Team Owner
Joined: Feb 2006
Posts: 24,460
Likes: 7
From: sw Ohio
Code 15
After adjusting my valves on my '85, the car gave me code 14 and 15 on startup. I replaced the connector and wiring to the coolant sensor and now I'm still getting code 15. The car runs around 400 rpms and will stall until it gets warmed up if I dont give it some gas. It feels like it has no power and its missing. My dad said it sounds like the timing is off. So I bought a timing light, but i've been told code 15 could mean a bad ECM. I was wondering if anyone else has experienced a similar problem and has advice before I go and waste money.
Melting Slicks
Joined: Nov 2005
Posts: 2,736
Likes: 0
From: WAY UPSTATE NY
code 15 = high voltage to the CTS. You seem to be having alot of trouble with timing this car.What condition is your timing chain in?Next time you have the spark plugs out pop off the distributor cap.Note where the rotor is pointing,then turn the balancer one direction until the rotor moves a little,then turn the balancer the other way.If the rotor does not move right away you have a strectched timing chain or lost some nylon off the cam gear. A little strecth is ok but you might be surprised at just how far it can stretch and the car still run. I have seen them wear thru the timing cover and still run.
Thread Starter
Team Owner
Joined: Feb 2006
Posts: 24,460
Likes: 7
From: sw Ohio
The timing chain is in good shape, the engine and rotor turn and there is no slack. I just cant figure out if its the coolant sensor, the ECM, or the timing. I dont want to throw parts at it and end up wasting a bunch of money.
Le Mans Master
Joined: Feb 2006
Posts: 8,753
Likes: 9
From: Louisiana
The "ECT" (Engine Coolant Temperature) sensor or CTS (Coolant Temperature Sensor) monitors engine coolant temperature and sends the ECM a resistance signal that affects the ECM control of fuel mixture and ignition timing. This sensor, located in the front of the intake manifold next to the CSV switch, can be ohmed. It can be ohmed mounted in the intake manifold or outside in your hand. This is a temperature sensitive sensor. Buy using a ohm meter and touching the two terminals on the sensor with the ohm meter leads you will get a number. This number will vary with temperature. The colder the temp the higher the number and vise versa. Use the FSM to get the answer or post back the ohm's it read and the temp (engine or outside) the sensor was. Say at 70*f the sensor should read 3,400 ohms. Check the connection.
Team Owner
Joined: Jan 2003
Posts: 20,316
Likes: 246
From: Summerland B.C. Canada
If you follow the flow charts, it will shorten your list of possible problem parts. 
http://members.shaw.ca/corvette86/Code%2014.pdf
http://members.shaw.ca/corvette86/Code%2015.pdf
http://members.shaw.ca/corvette86/Code%2014.pdf
http://members.shaw.ca/corvette86/Code%2015.pdf
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
If you haven't found the problem, 15 means that the ECM is seeing and impossibly high temp from the sensor - about 300 degrees. More likely than not, the signal wire (yellow) is grounded somewhere between the sensor and the ECM - particularly if you've allready replaced the pigtail. Confirm it by disconnecting the harness from the sensor. That simulates a 14, but if the 15 remains, you'll need to troubleshoot the yellow wire back to the ECM.