06-03-13, 10:12 PM
I'm one who is always trying to help, but now I'm stumped on this one...This is a 94 Fleetwood.. It all started when the check engine light came on... It was code 63 and 64. So I put in a new O2 sensor on bank 2.. Then after that I just get a 63 code.. So I put in another O2 sensor, because I had one, same thing code 63... So just for the hell of it I changed the PCM, same thing code 63.. Put the old pcm back in.. and checked all the wires , no shorts and 12 volts to the heater ... With my cheapo meter I checked the voltage from 1666 and 1667 and got .62v, then I went on another no problem 94 and checked the voltage and got the same readings , everything checked the same readings...There has got to be something I'm missing... Dave
06-03-13, 11:59 PM
Hmmm. I researched it a bit and came up with this. "An O2 sensor failure or a problem in the sensor’s
wiring circuit will prevent the system from going into
closed loop causing a rich-fuel condition, increased
emissions (particularly carbon monoxide) and fuel
consumption. Keep in mind that a bad coolant
temperature sensor can also prevent the system from
going into closed loop."
Maybe something to do with the coolant sensor?
06-04-13, 12:36 AM
The book says it won't set a 63 code until it reaches 180 something degrees. so it can't set the code until it thinks its hot..
Was that the LT1?94 Fleetwoods come with LT1.
06-04-13, 03:59 AM
What brand 02 sensors? Aftermarket might not work right.
06-04-13, 08:28 AM
Use the HVAC unit to see what the coolant temp sensor is reporting. It's option #8.
06-04-13, 10:29 PM
I may have more problems.. Went to check the temp sensor and it would not start... No spark.. changed the module , still no spark.. Plugged the old module back in and took off the coil wire to check ohms.. checked good, put a new one on anyway... Started right up.. still don't think it was the wire , I will try the old one later... Started it up , let it run and it the temp went right up just like it should... Now this 63 code is only set went its running and turns on, after I shut it off the code is gone and don't come on for miles...
94 Fleetwoods come with LT1.
Clearly... I didnt know if it also had an L99 option as well
06-05-13, 02:10 AM
Hmmmm. Maybe there is a bit of intermittent weak spark on that bank which would prevent it from going into closed loop?
06-09-13, 05:55 PM
Well I got the no spark and then spark again thing fixed.. The no spark can be caused by no pulse from distributor, but there are two pulses and if it were a no pulse it would set a code. So we can rule that out. I had swapped out the module when it had a no spark , and it did not work.. So rule out the module.. So now it leaves the coil... I check the coil with a ohm meter and all tests look good.. It was tested with a cheap harbor freight meter... Here is another thing I noticed when it was running and then not running and then running again, when in park and just revved up the motor it had a bit of a backfire through the exhaust, kind of like a cheap muffler sound.. So I put a new coil on and also I used a know to be good module just in case... Now it runs great.. Even though the coil tested good with the meter it was bad...The muffler sound is back to normal.. So now I will report back and see if this was related to the code 63 problem.. Dave
06-10-13, 01:59 AM
I hope it works out for you. I wonder how long does it take for the computer to turn off the check engine light once it goes into closed loop operation.