code 15
Thread Starter
Instructor
Joined: Mar 2004
Posts: 141
Likes: 0
From: Burbank IL
code 15
Ok i have been having this code for a couple months now i replaced the sensor and it went away for a couple of weeks but then I started getting it again. So i replaced the connector going to the sensor but it didn't help. with the car in run im getting 5 volts from the yellow wire and ground from the black. I started the car with a voltmeter hooked up to the yellow wire and to ground the voltage started off at 1.69 it was about 85 degrees out and steadily went down to 1 then jumped up to 3 and started going down again this is when the ses light comes on so I turned off the car started it again no light came on right away the voltage off of the yellow wire was 3 slowly went down to 2 and the ses light came back on. im not sure what else I need to do to fix this anyone have any ideas
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
You can check voltage at the ECM pinouts to make sure they're the same and you can scan it. Sounds like a funky ECM though. When mine went, the scan showed that it was toggling between 220 and 250 degrees regardless of engine temp or sensor voltages - they were normal at the pinouts. I guess I could have opened up the case, but I wouldn't know what I was looking at or to look for on the Board, so it just became obvious that the ECM was gone.
Team Owner
Joined: Jan 2003
Posts: 20,254
Likes: 221
From: Summerland B.C. Canada
Team Owner
Joined: Jan 2003
Posts: 20,254
Likes: 221
From: Summerland B.C. Canada
Racer
Joined: Sep 2007
Posts: 393
Likes: 0
From: Bartonville Illinois
I don't know how much difference there is between a 1990 and a 1993.
On my 1993, when you start the car and its cold the voltage at the sensor will be at a certain level and start going down as it warms up. When it reaches a certain point the ECM will change the scale internally to make the reading more accurate at normal temps. It still needs to stay between 1.5 and 2 volts to stay in range.
The sensors seem to break down some after repeated heating and cooling. If you can force a 14 thats a good sign. Clear the code and unplug the sensor. If you get a 15 pretty soon the sensor is probably bad. I have checked several of these sensors in hot and boiling water at the same time and at different temps. Some react quicker than others and some "Never" reached the resistance level they should to send the proper voltage to the ECM.
On my 1993, when you start the car and its cold the voltage at the sensor will be at a certain level and start going down as it warms up. When it reaches a certain point the ECM will change the scale internally to make the reading more accurate at normal temps. It still needs to stay between 1.5 and 2 volts to stay in range.
The sensors seem to break down some after repeated heating and cooling. If you can force a 14 thats a good sign. Clear the code and unplug the sensor. If you get a 15 pretty soon the sensor is probably bad. I have checked several of these sensors in hot and boiling water at the same time and at different temps. Some react quicker than others and some "Never" reached the resistance level they should to send the proper voltage to the ECM.
Racer
Joined: Oct 2005
Posts: 343
Likes: 0
From: San Antonio Tx
hi
HELP, new to C4 - what buttons do you push to find codes. Do I need to buy something?? ooops have 95 LT 1 m6 -SLP Claw, headers,whole exhaust, new wires, plugs, belt, slotted/ drilled rotors - Rotors were a piece of cake - the rest wooooow what a job - but she is running great, just need some more RWHP --
C5 is easy, but dont understand on the C4 - appreaciate any help - just an ole gear head - can do all the nuts and bolts but this electrical stuff is tough.
Len
HELP, new to C4 - what buttons do you push to find codes. Do I need to buy something?? ooops have 95 LT 1 m6 -SLP Claw, headers,whole exhaust, new wires, plugs, belt, slotted/ drilled rotors - Rotors were a piece of cake - the rest wooooow what a job - but she is running great, just need some more RWHP --
C5 is easy, but dont understand on the C4 - appreaciate any help - just an ole gear head - can do all the nuts and bolts but this electrical stuff is tough.
Len
Last edited by lenbal; Jun 13, 2008 at 05:46 PM. Reason: forgot yr
