I have an 88 iroc vert w/ LB9 that gave a code 14 so I changed out CTS and cleared out the codes, a little while later code 14 came again, I cleared it. I keep doing this over and over. what's wrong with this thing. anybody?

The code '14' is for a CTS reading that is considered to be an impossibly high temperature. Given that the ECM will interpret the resistance at the CTS according to this table:



Anything below 5 or over 100K ohms is considered out of range. A disconnected sensor will obviously be above 100K, thus creating a '13', and a shorted connector or wire harness will create a resistance below 5 ohms, and thus set the '14' error code. You may want to check the resistance of the sensor while unplugged to make sure it is relatively close to the table. If you have cleared the error codes, and the error persists, you may want to measure the resistance of the connector and wire harness to be certain it isn't shorted.

thanks Vader, I'll try that. I sort of ruled out the wiring and connectors, I bought the car new in 88' and its been untouched since then, so theres never been several personalities (owners)under the hood. All I've ever done to it is drive. It also has some idle issues, it wants to idle @ 1000 instead of 750

I disconnected the cts plug and checked the sensor itself and got 754 ohms (135 degrees) I ran the engine some this afternoon so thats about right. Then I plugged the cts back in, pulled the ecm out disconnected the plug and checked back to the cts and got 713 ohms. So, this means no break in the wires right? Is my ecm bad?

The next thing you should do is check the reference voltage at the sensor. The yellow wire should have 5.0 VDC referenced to a good engine ground when the sensor is disconnected.

That check turned out 5vdc on the nose. It just don't make sense, after sitting over nite, when you start the motor up it runs really crappy for about 5 or 10 seconds , it seems like the longer it runs the better it runs

If you have 5V dead on, the connection to the ECM from the CTS connector is apparently intact and not shorted. Further, the sensor seems to be within a reasonable resistance range.

Just for grins, you can disconnect battery power overnight to fully dump RAM contents. At least you'll be starting with a completely cleared ECM.

My 91 GMC Jimmy started throwing mystery Code 14s a few years back. Sensors, ECMs and such made no difference. Ultimately, I found that one of the engine brackets that the wiring harness ran past had (over 200K miles of driving) worn through the plastic wiring conduit, through the insulation on the CTS wires inside and would ground them out intermittently against the bracket causing the code.

The tip-off towards the end was that I could idle it all day in the driveway without a problem but as soon as I threw it in gear, stepped on the gas and the engine torqued over a little in it's mounts I could count 2-Mississippi and the light would pop on. The rest was just tracing the wire from the sensor back until I found the damage. Likewise, my motor was all stock/original and never messed with by a previous owner.

BTW- you ARE replacing the sensor in the intake manifold (the 2-wire CTS) and not the one in the head that runs the gague (1 wire), right?

yeah, its in the intake i'm certain its the cts sensor. I have a feeling this is going to take awhile.

yeah, its in the intake i'm certain its the cts sensor. I have a feeling this is going to take awhile.

Borrowed friends snap-on scan tool tonite and found alot out. The ecm for some reason thinks the engine is over heating. I think code 14 is 284 deg for over 20 secs. This was the case, BUT fully warmed up with one fan "jumped to run" it can go forever and the scan tool indicates 260 deg steady but the engine is actually more like 195 deg. What the crap does this mean?

Unplug the sensor and see what it reads on the scan tool. Should be -40F. If not, you've got SOMETHING not working right (wrong CTS sensor, still possible wiring damage??).

Follow through is the key to a successfull forum. I'm dragging this thread back to list what the problem was. Always try to come back and post if it was solved, other wise people with similar problems will just have to keep searching. My ecm was bad, it was adding 50 degrees to the cts reading. The snap on scanner had two cts tests it failed one repeatedly and passed the other. Unplugging the cts with key on, engine off scanner reading should be between 20deg. to -40 deg my was 198. Changed ecm, now runs better than it has in years. Thanks guys