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Reverse the overdrive ON/OFF switch?
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Bort
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Nov 28, 2014, 3:02 AM
Post #1 of 14
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Reverse the overdrive ON/OFF switch?
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I have an '05 Jeep Liberty. I've learned the hard way that the transmission in these vehicles are very sensitive and require overdrive to be used properly. I know too many people who own these same vehicles that don't use O/D properly (or at all) and they replace their damaged or destroyed transmission at least once a year if not every few months because they're driving around in overdrive all the time.
When the vehicle is started it starts with overdrive ON. Is there a way to reverse the switch, perhaps the wiring to it, so when it's started it starts with overdrive OFF?
The more I think about it the more tempted I am to try it swapping the wires from one post to the other but I don't want to cause myself expensive repairs because doing so will screw something up.
Since these tranny's are so sensitive to being in overdrive all the time it makes no sense to me why it's ON when the engine's started.
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Tom Greenleaf
Ultimate Carjunky
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Nov 28, 2014, 5:03 AM
Post #2 of 14
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Re: Reverse the overdrive ON/OFF switch?
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Don't mess with it till you read how to operate or defeat OD as a would be or should be suggested in owner's manual. If you aimlessly just alter wiring for things you risk causing a host of other problems. If this vehicle is not operating and shifting as intended that's a repair issue or you own the wrong vehicle for what you want or need,
T
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Hammer Time
Ultimate Carjunky
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Nov 28, 2014, 5:42 AM
Post #3 of 14
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Re: Reverse the overdrive ON/OFF switch?
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I don't know what you are doing to destroy these transmissions but this is not something we see a lot.
These vehicles do not start off in overdrive. Overdrive is an addition gear that engages at a specific speed, usually done by locking the torque converter to a 1:1 ratio. On vehicles where overdrive shouldn't be used under certain conditions, like towing, the vehicle has a manual shut off switch.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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Bort
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Nov 28, 2014, 1:41 PM
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Re: Reverse the overdrive ON/OFF switch?
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(Tom Greenleaf)
Don't mess with it till you read how to operate or defeat OD as a would be or should be suggested in owner's manual. If you aimlessly just alter wiring for things you risk causing a host of other problems. If this vehicle is not operating and shifting as intended that's a repair issue or you own the wrong vehicle for what you want or need,
T I don't have an owners manual. I've downloaded it though and it's not very informative on how to operate OD. I know how to operate it because I'm an observant-to-my-vehicle driver and know I'm operating it correctly. The times that I've made mistakes and didn't operate OD correctly, which are few accidental presses of the OD button turning it off while going too fast for the lower geared mode, tell me I am using it the way it's meant to be used. It's shifting fine, and I'm using it the way it's intended. I just thought you guys here were experts. All I want to know is if swapping what posts the wires are on will reverse the switch so when the vehicle is started it starts with overdrive mode OFF instead of ON.
Anyone can buy whatever vehicle they want. The U.S. is still a free country.
(Hammer Time)
I don't know what you are doing to destroy these transmissions but this is not something we see a lot.
These vehicles do not start off in overdrive. Overdrive is an addition gear that engages at a specific speed, usually done by locking the torque converter to a 1:1 ratio. On vehicles where overdrive shouldn't be used under certain conditions, like towing, the vehicle has a manual shut off switch.
Sir, you could not be further from wrong. First, I have had this vehicle for 2 years now and haven't even once had to replace the transmission. It runs and shifts great and I maintain everything on the vehicle as necessary. I know other people that have the same make, model, and year that don't use overdrive properly. They are the ones destroying and replacing their tranny once a year or more.
Secondly, wrong again, it very much does start with overdrive engaged. I know because I drive it every day. The light for it in the dash says "Overdrive OFF" when lit and the light goes out when overdrive is engaged. When the vehicle is started the dash light is not displayed therefore overdrive mode is ON. Torque converters also do not shift. They do as they're named. They convert the torque from the engine to the transmission so the pinions don't get damaged or ripped off from too much power being applied.
Thank you for your answer. Maybe others do start with overdrive mode off. These jeeps don't. They start with it on.
I've learned the hard way that the transmission in these vehicles are very sensitive and require overdrive to be used properly. (Discretesignals) Just curious, but how did you learn this?
LOL! By accidentally pressing the OD mode button over 45mph, and forgetting to turn it back off for lower gear mode to pull out/city driving at stops. The RPMs scream, and shifting acts up for about 50 miles of using it properly again then it corrects it self.
Thanks for the answers guys. But the answer to my question is simple:
Yes, swapping the wires reverses the switch.
No, swapping the wires will damage *this*.
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Tom Greenleaf
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Nov 28, 2014, 1:55 PM
Post #6 of 14
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Re: Reverse the overdrive ON/OFF switch?
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Beat on this a bit more. There are times you defeat OD for reasons as already mentioned but repeat. Hauling a trailer perhaps, driving at a speed where it's constantly locking converter (that's what it's doing that feels like another gear) because you are at just the certain speed and just hills have it confused it feels lousy so cancel it for just those times.
It's an automatic and pretty good a choosing the correct gear for the load and speed - most are. Sorry if the thing starts off with it on as most people would appreciate and defeat when called for as you can. So what's the problem? Seems you just want that feature to default the other way and I'm telling you that once you start messing with it you are asking for troubles. Something else could be involve giving it adverse changes from the original design. If it was that much of a common complaint it would have likely been recalled and redone by engineers and I know of know such thing.
Each of us drive in our own assorted conditions. This still provides you choice and again I say you are just opening Pandora's box messing with it,
T
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Bort
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Nov 28, 2014, 3:36 PM
Post #7 of 14
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Re: Reverse the overdrive ON/OFF switch?
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Do you know if OD mode on/off is just switch, button, LED in the dash, fuse, and a wire? (meaning swapping the wires is going to do exactly what I think it will do)
Or are there chips and/or relays involved too? (meaning it's best to not mess with it unless I rebuild the chip and relay so they can handle reverse polarity, which I am very well capable of doing.)
I'm looking for a detailed answer. If nobody here knows, I can extend my search to other forums in hopes to find someone that does. I appreciate the answers I've gotten, very much. Thank you. But so far they've been could and maybe's. Not specific knowledge-filled, detailed, (true expert) 'yes, can be done that way.' or 'no, *this* is there too and you'll damage it.'
If I'm not able to find that level of answer here I'll extend my search for the answer to other resources and hope to find it there. I gave your forums a shot at it. Nice site, good intentions, thank you.
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Bort
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Nov 28, 2014, 3:39 PM
Post #8 of 14
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Re: Reverse the overdrive ON/OFF switch?
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What do you mean by Defeat Overdrive, Tom?
Turning it off?
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gsferraro
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Nov 28, 2014, 4:09 PM
Post #9 of 14
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Re: Reverse the overdrive ON/OFF switch?
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What is the engine size or the vin of this jeep, im going to look at a wiring diagram to see whats going on. In my opinion, the way i see these wired, i dont think you can do this, but i will check. Gary
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Bort
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Nov 28, 2014, 4:16 PM
Post #10 of 14
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Re: Reverse the overdrive ON/OFF switch?
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Thanks. 3.7L
4x4 (shifter, not button 4wheel)
I don't know the vin off the top of my head.
If the schematics are online please share. Much appreciated!
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Discretesignals
Ultimate Carjunky
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Nov 28, 2014, 4:59 PM
Post #11 of 14
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Re: Reverse the overdrive ON/OFF switch?
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I can tell you right now without looking at a wiring diagram that the momentary O/D switch is either going to pull down or pull up a certain voltage that the PCM/TCM senses to determine if the switch is triggered. Reversing the wiring is not going to have any affect on its operation. You would either have to change the logic in the software or hardware inside the controller to reverse how it defaults when the ignition is cycled.
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
(This post was edited by Discretesignals on Nov 28, 2014, 5:05 PM)
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gsferraro
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Nov 28, 2014, 5:11 PM
Post #12 of 14
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Re: Reverse the overdrive ON/OFF switch?
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Bort,
I have a transmission shop, i have shopkey pro and mitchell on demand(i pay monthly for this service) i do eletrical work on transmissions all the time.
The shifter assembly has a 6 pin connector. Pin 3 of the shifter assembly goes to the pcm for the o/d off switch, pins 2 and 4 are grounds, one for the overdrive switch and one for the light(2 wires one ground location). It looks like in order for the computer to cancel o/d it needs to see 12 volts on pin 17 of the C4 connector(pin3 on shift assembly pin 17 at pcm c4 connector). It must cancell o/d through a driver inside the computer. Im honestly not sure what would happen as i never tried this, but i would think you would never be able to cancell o/d and maybe the o/d off light would constanly stay lit. Im also not sure if any damage would occur to the computer or the circuit board in the instrument cluster.
Im just wondering what were your plans, to cut and splice or take the wire from the connector and switch them. I would be careful, it looks like the grounds are all together under the drivers seat. Gary
(This post was edited by gsferraro on Nov 28, 2014, 5:42 PM)
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Discretesignals
Ultimate Carjunky
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Nov 28, 2014, 5:49 PM
Post #13 of 14
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Re: Reverse the overdrive ON/OFF switch?
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So basically the PCM sends a 12 volt signal that the PCM monitors to the OD switch to see if it is being depressed or not.
It's is not a driver circuit, but a sense circuit or input circuit. A driver circuit is a transistor type circuit that is used to control an output of some type. The OD switch circuit is a 12 volt circuit with an internal resistor and a voltage sensing circuit that the PCM processor uses to tell if the switch is pressed. The circuit is grounded when the button is depressed. The sensing circuit will either see 12 volts on the circuit which means the button is not being pressed and will see 0 volts on the circuit when the switch is pressed. You can reverse the switch side of the circuit but it won't have any affect because the switch isn't polarized. If you continually ground the circuit, the PCM is going to generate a trouble code for an OD switch circuit problem.
The internal resistor inside the PCM on the circuit is there so you don't fry the circuit when it is grounded by the switch or a short to ground. Like I stated the only way to reverse the operation of the switch is to change the software or change the logic if it is hardware controlled.
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
(This post was edited by Discretesignals on Nov 28, 2014, 6:02 PM)
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Hammer Time
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Nov 28, 2014, 6:01 PM
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Re: Reverse the overdrive ON/OFF switch?
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Maybe someone just needs to teach him how to operate his controls.
Isn't the overdrive off light working as a TCM malfunction indicator when it flashes? Maybe someone should be checking the TCM for codes here and find out why it is doing that.
An overdrive off indicator is standard equipment on all instrument clusters. However, on vehicles not equipped with the optional overdrive automatic transmission, this indicator is electronically disabled. This indicator is located above the fuel gauge and to the left of the speedometer in the instrument cluster.
The overdrive off indicator consists of a stencil-like cutout of the text "0/D OFF" in the opaque layer of the instrument cluster overlay. The dark outer layer of the overlay prevents the text from being clearly visible when the indicator is not illuminated. An amber Light Emitting Diode (LED) behind the cutout in the opaque layer of the overlay causes the "0/D OFF" text to appear in amber through the translucent outer layer of the overlay when the indicator is illuminated from behind by the LED, which is soldered onto the instrument cluster electronic circuit board.
When the exterior lighting is turned On, the illumination intensity of the overdrive off indicator is dimmable, which is adjusted along with the cluster illumination lighting using the panel lamps dimmer control ring on the left control stalk of the multifunction switch. The overdrive off indicator is serviced as a unit with the instrument cluster.
The overdrive off indicator gives an indication to the vehicle operator when the Off position of the overdrive off switch has been selected, disabling the electronically controlled overdrive feature of the automatic transmission. This indicator is controlled by a transistor on the instrument cluster circuit board based upon cluster programming and electronic messages received by the cluster from the Powertrain Control Module (PCM) over the Programmable Communications Interface (PCI) data bus.
The overdrive off indicator Light Emitting Diode (LED) is completely controlled by the instrument cluster logic circuit, and that logic will only allow this indicator to operate when the instrument cluster receives a battery current input on the fused ignition switch output (run-start) circuit. Therefore, the LED will always be off when the ignition switch is in any position except On or Start. The LED only illuminates when it is provided a path to ground by the instrument cluster transistor. The instrument cluster will turn on the overdrive off indicator for the following reasons:
- Overdrive Off Lamp-On Message - Each time the cluster receives an overdrive off lamp-on message from the PCM indicating that the Off position of the overdrive off switch has been selected, the overdrive off indicator will be illuminated. The indicator remains illuminated until the cluster receives an overdrive off lamp-off message from the PCM, or until the ignition switch is turned to the Off position, whichever occurs first.
- Actuator Test - Each time the cluster is put through the actuator test, the overdrive off indicator will be turned on, then off again during the bulb check portion of the test to confirm the functionality of the LED and the cluster control circuitry.
The PCM continually monitors the overdrive off switch to determine the appropriate outputs to the automatic transmission. The PCM then sends the proper overdrive off lamp-on and lamp-off messages to the instrument cluster. For further diagnosis of the overdrive off indicator or the instrument cluster circuitry that controls the indicator,
For proper diagnosis of the overdrive control system, the PCM, the PCI data bus, or the electronic message inputs to the instrument cluster that control the overdrive off indicator, a diagnostic scan tool is required.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
(This post was edited by Hammer Time on Nov 28, 2014, 6:05 PM)
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