I posted this problem a few weeks ago and haven't gotten a response, so I guess I'll try again.
I have a 1994 YJ w/ a 2.5l engine and keep getting a code 22 with the check engine light. I have replaced the temp sensor 2 times, checked the current in the plug with a multimeter (got 4.95v), checked the ohms on the sensor and it cycles between 867 and 975 (depending on when the thermostat opens and closes), and I have had the local schools auto shop hook into the computer and clear the code.
The jeep runs fine for about 30 mi. (Strait driving without many stops) and then the check engine light comes on, and the rpms hover around 1500 when I am stopped and have the clutch in. Everything else seems to be fine. What am I missing? Has anyone else encountered this problem?
Code 22: Displays ECT SENSOR VOLTAGE TOO LOW. Condition is: Engine Coolant Temperature (ECT) sensor input less than minimum acceptable voltage.
ECT SENSOR VOLTAGE TOO LOW .................................. FC-13A
TEST FC-13A - ECT SENSOR VOLTAGE TOO LOW
NOTE: For connector terminal identification, see CONNECTOR
IDENTIFICATION at beginning of article. For wiring diagrams,
see L - WIRING DIAGRAMS article in the ENGINE PERFORMANCE
1) Using DRB-II, read Engine Coolant Temperature (ECT) sensor voltage. If voltage is less than .5 volt, go to step 4). If voltage is more than .5 volt, wiggle wiring harness from ECT sensor to Powertrain Control Module (PCM) while observing DRB-II. If voltage changes, repair wiring harness as necessary. Perform TEST VER-1.
2) If voltage does not change, condition required to set fault is not present at this time. ECT SENSOR VOLTAGE TOO LOW fault sets if ECT sensor signal circuit (Tan/Black wire) is less than .5 volt. Possible causes are: short to ground in ECT sensor signal circuit (Tan/Black wire) or ECT sensor shorted internally. Go to next
3) Inspect all related wiring and connectors and repair as necessary. Perform TEST VER-1. If no problems were found with wiring
and connectors, see INACTIVE FAULT CONDITION. Perform TEST VER-2.
4) Disconnect ECT sensor connector. Using DRB-II, read ECT sensor voltage. If voltage is more than 4 volts, replace ECT sensor.
Perform TEST VER-1. If voltage is less than 4 volts, turn ignition off. Disconnect PCM connector.
5) Put DRB-II in ohmmeter mode. Using DRB-II, check resistance of ECT sensor connector, signal circuit (Tan/Black wire).
If resistance is more than 5 ohms, replace PCM. Perform TEST VER-1. If resistance is less than 5 ohms, repair short to ground in Tan/Black
wire. Perform TEST VER-1.
I changed both, but the one I am having trouble with is the one closest to the tstat housing. I got the first coolant sensor from Autozone, and after exchanging it twice, went to NAPA and picked one up from there. The one at the tstat housing has 2 contacts and the one against the firewall to the gauge has just one contact.
It has been a few weeks since I replaced the CTS, I have just been chasing other possible causes for the code. Funny thing though, went out and moved the jeep out of the garage this evening to get to something else, and the light did not come on. Maybe I'll take it in to work tomorrow to see if the code comes back.
Does the code normally go away without clearing it from the ECM?
Last edited by jakedillard; 11-06-2012 at 10:31 PM..
It will clear after 50 key cycles or after a batttery reset. It will not always light the CEL. That is why I asked if you disconnected the battery to clear the fault and took it for a drive long enough to let it go into closed loop and see if the problem is solved.
Thanks for all the responses. The last 2 times I was able to get the code to clear (had the high school auto shop hook it up to their computer to clear it), I took it out and after about 30 miles of continuous driving the light would come back on. This last time when the light came back on the engine stayed at around 1500 rpms when I would get to a stop and push in the clutch and took about 30-45 seconds to slowly drop down to the normal idle speed.
This last time I did nothing to clear the code and after sitting about a day the CEL wen't off on its own and hasn't come back on since (I have only driven it to work which is about 11 mi one way). I am just wondering if the problem has corrected itself or if the next time I take it out hunting or something the problem will return.
Code 22 is back again. Jeep has been running fine for about 3 months and the last time we took it out, drove it all day and just before getting home the light came back on. This is getting frustrating. Went through all the checks again, ohms are correct and volts running around 4.95. Is it possible there is a short in the wire and this is what is causing the issue. Did the key cycle to get the code and then disconnected the battery and put positive to ground so as to drain the capacitor and light comes back on right at start-up. What else can I do here short of going through and replacing the plug and wiring? Thanks for all of the help.
I sort of figured. It probably is wiring. First pull the connector on the ecu/ Check pin 21 and make sure it is not loose. Remove the backshell for the ecu connector and check it to make sure there is nothing shorting it out. If they look good after you inspected them them you can run a wire from the sensor signal directly to the ecu pin 21 black/red. Open it on both sides on the wire harness and leave a 2" pigtail in the harness and just attach a 18 or 20 guage wire directly beween the two sides.