QuestionQUESTION: 2003 Town car ,bought it new has over 300k (i'ma limo guy)runs great. First,
"service engine soon" light came on,then following day od/off light starting
blinking.Tranny shifts great,smooth,fluid level fine.Mechanic checked the codes it
showed p0705 & p1702 (transmission range sensor) replaced that and speed sensor
(conectors seemed fine) just in case because i read that for some people that was a
solution.No change,light still on od/off still blinking.I noticed that there is more
rav to the engine(rpm higher,a bit louder) when in drive ,shifts smooths as always
overdrive working(never stoped) when i put in neutral or park after 10 seconds
engine quites dowm rpm drops and od/off light disappears.The only thing ever done to
tranny in the past was replacing torque converter(It was typical vibration
issue)Please help Is it TQ again,some relay ,tranny,computer...Thank YOU!
ANSWER: Hi Dali,
There are many possibilities for this issue.
I will outline the most likely causes below.
1. The OD switch is malfunctioning and causing the OD/off light to come on (given that the engine idle changes though i doubt this is the problem, but worth looking into just incase)
2. Engine idle sensor may be malfunctioning, this is easily replaced/repaired and can sometimes cause the idle problems you speak of.
3. The TQ may be having issues again, remember the vehicle has 300K on it, so this is a very likely possibility.
4. The relay going from the OD switch to the dash light may be having issues, also easily fixed by replacing or repairing it.
5. The other thing that may be happening is that the transmission sensors that run to the shift control at the steering wheel may be having problems. The relay could be causing the vehicle to come out of OD when you don't want it to because of an electrical problem at the transmission, this will cause the RPM to go higher as you are basically shifting into a different gear requiring more torque and will cause the OD/off light to come on. And when the vehicle goes into neutral or park, the light would stop blinking because your transmission relay is recognizing that the vehicle is no longer in drive, which would lower the rpm.
I would recommend checking the above options first and let me know how you make out, then from there we can get more involved into diagnosis if needed. Keep in mind, most of the steps above will need to be checked by a mechanic or certified automotive electrician as they are very intricate and require the use of special tools and a lift in most cases.
I hope this helps you.
Thank you
Please let me know how you make out.
---------- FOLLOW-UP ----------
QUESTION: Hi Antonio,
Thank You very much!
I understand that there is so many options and that's what's driving me crazy.One thing that i missed to mention is that i replaced battery yesterday because the old one was bad and barely started my car(also there was a lot of acid on terminal) Anyhow, update on my adventure:
Today i went to a shop that friend of a friend manages,so they hook it up to a computer it showed only 705 code(mechanic said that he will not erase the code so people at transmission place would know what is going on),then they send me to a transmission place nearby.On my way there i noticed that od/off light is not blinking and rpm's are fine,but i thought ok maybe because it was a really short ride(even though so far it would happen really quick once in drive).Hooked up to a computer at transmission place ,now showing no codes,guy checked the memory and saw the code and said it could be a computer,tranny,and like you said Antonio list goes on and on...I'm thinking ok i'll drive it and i'm sure it will happen again really soon so i'll schedule appointment that they can try to find out what is causing all this.Sure enough after 10-15 minutes of driving od/off light blinking again ,i stoped at the traffic light put it in neutral rpm's go down light dissapers,few more times like that and afterwards everything was fine i drove another 20-30 miles stoping several times and turning off the engine.CRAZY RIGHT?.I'll see what happens tommorow.I talked to my neigbhor and he said that another option could be alternator going bad and working hard and not producing proper voltage so computer is getting confused and that could be the reason for acid on the old battery.Then again it could be a short someplace.EVERYTHING IS POSSIBLE!!!I really hope that it doesn't happen again but i'm really traumatized by this experience.THANK YOU SO MUCH ANTONIO I WILL LET YOU KNOW WHAT HAPPENS AND IN CASE IT HAPPENS AGAIN I'LL FORWARD LIST OF POSSIBILITIES THAT YOU MENTIONED TO A PERSON THAT DOES DIAGNOSTICS ON THIS ENIGMATIC CAR OF MINE.THANK YOU!!!CHEERS!
DALI
AnswerHi Dali,
From what you have just told me i would say that the problem is most likely in one of three places
The alternator, like your neighbor said
The Computer
The Transmission
I would start with having these checked.
I would have your mechanic, or better yet an automotive electrical repair shop run a full systems check and diagnostic on the ECM (Electronic Control Module) Often referred to as the computer, to look for faults that could cause the tranny to slip out of OD since your cars transmission should be electronically controlled as is the OD Sensor.
I would take the car to auto zone or advance auto and have them run a check on your alternator, this is free for them to do, and will quickly tell you if there is a problem in the alternator, don't be afraid to ask him to explain the results either, theres no shame in asking for further explanation, if he cant explain it to you, ask for a print out of the results and bring them to your mechanic for further explanation.
If the above two are fine i would focus on the tranny, specifically the sensors that regulate the Drive and OD functions of the tranny. Start there and let me know how you make out.
Thanks Again
