Seat Position Sensor

[Taffy]

So in my search for an answer (see another post about a strange acting power seat), I came across a land rover forum where someone had the same problem as I have. They didn't say whether their issue was finally sorted though.

 

Does anyone know where exactly to find the seat position sensor and what it looks like?

 

Many thanks

[SpAwNtoHell]

Hy taffy, will try to dig out through what i have about the car in the workshop manual but i do not think is related to position sensor but the switch itself, i will have a look and see what i can find, actually i will check my car also as i always used the memory.

 

And yes i know the feeling about geting a blank when it comes down to this model

Edited May 15, 2018 by SpAwNtoHell

[Taffy]

Thank you SpAwNtoHell. I appreciate all the help I can get. It is not the switch though. There are four switches on the pcb, two sets of twins. Only one switch was suspect, but interchanging it with the other one made no difference at all.

[SpAwNtoHell]

I will have a look at my one but is not back yet... that p0740 is pest... 2 weeks already... i have the schematics but to be fair it looks weird how they choosed to represent it... now thinking about it might have the same issue as i remember adjusting drivers seat first time... did not touch it sice tho...

[Taffy]

Oh. I just googled p0740 code. I got this: When the code P0740 is set in the Powertrain Computer, it means that the Powertrain Computer or PCM is seeing greater than a 200 RPM difference between the rotational speed of the Torque Converter and the Transmission Input Shaft.

 

You clearly know your way around cars, but this sounds like a possible fix by replacing the trans fluid?

[SpAwNtoHell]

Oh. I just googled p0740 code. I got this: When the code P0740 is set in the Powertrain Computer, it means that the Powertrain Computer or PCM is seeing greater than a 200 RPM difference between the rotational speed of the Torque Converter and the Transmission Input Shaft.

 

You clearly know your way around cars, but this sounds like a possible fix by replacing the trans fluid?

 

P0740 on this gearbox is...  TCC out of range, if other codes gearbox related are present is a electrical issue usually wiring or ground straps, if code is alone... gets complicated, can be the solenoid, the gearbox oil pump or torque converter.

When in 2nd, 3rd, or 4th gear, the Torque Converter Clutch (TCC) can be locked or partially locked when certain conditions are met. The TCC piston is electronically modulated by increasing the duty cycle of the LR/TCC solenoid until the torque converter slip difference (difference between engine and turbine speed) is within 60 rpm...so when greater MIL is illuminated if is sliping to much... The lock is for fuel economy but also to signal the start of a mechanical failure...before it gets bad.

 

Anyway leaving that aside...back to the seats... guess what i have the same issue... and the documentation that i have only includes schematics and how to remove seat and install... From the schematics i do not see any sensors only switches and a module? so seems i am not a lot of help... if wiring diagram would be any help to you let me know.

[Taffy]

Thank you. I am not sure which diagrams you are referring to. I have the T&C manual which doesn't cover diesel engines, and also the Chrysler Workshop CD Manual which again has schematics, but they only go as far as block diagrams. I should really double check this. However, if there are only switches and a module, then because the switches have already been eliminated as a possible cause, either the module is faulty or there is some issue with the wiring.

I guess my next step is to see if I can obtain a known functional module.

Although, it does occur to me that since you say you're experiencing the same problem then this is perhaps a known issue - and someone somewhere (probably working for Chrysler)  knows the cause and how to remedy it.

[SpAwNtoHell]

It might be something else like module setup settings adaption that i am not aware of. I have a version of alldata that covers town and contry and the dodge but as you say only covers petrol engines and not the voyager made for europe export, haynes book din not even bother to buy as is crap in my opinion, haynes pro database is not very helpfull either as covers specifics suitable for a garage that needs to replace stuff, the chrysler grand voyager dvd i have is the most complete but the wiring part is more wiring then a schematics database, which for me personally that if needed i can repair a pvb board at component level looks like child play. Is not schematic for the seat itsel, the wiring shows the wires going to the switches in the seat via plugs and thats it coming from a seat module. Obviously the modules has a power feed a ground and wires going to the seat but much more. At this moment in time i do not even know exactly where is located...not sure if module itself is corelated to other modules and comunicating with them and so on... witech probably could reveal more as far as i digged into it but even if i buy one is useless without acces to their global server network. Worse is we do not have where to get info. The town country except some parts is different from what we have in uk, yes we have the gearbox suspension and other bits core related but others were made specially for Europe.

[SpAwNtoHell]

Hmmm hey look i got a pdf about the seats... seems i was right... they can be verified via CAN, looks like it can be from the switch or module configuration

 

 

Power Seat Switch - Vehicles may be equipped with a driver side eight-way power seat switch. The power seat switches are paddle-type levers mounted on the outboard seat side shields. Movement of the seat cushions and backs mimics the action of the switch paddles. MEMORY SEAT SYSTEM An electronic memory seat system is available on certain models. The memory system is able to store and recall all driver side power seat positions, outside mirror positions and power adjustable pedal position. The system can be set for two different drivers. On vehicles with a factory installed radio connected to the Controller Area Network (CAN) data bus network, the memory system is also able to store and recall up to twelve radio station presets (six AM and six FM), for two drivers. The memory system will also store and recall the last station listened to for each driver, even if it is not one of the twelve preset stations. The memory system will automatically recall all of these settings when a button of the memory switch is depressed, or when the doors are unlocked using the Remote Keyless Entry (RKE) transmitter (if enabled). If the vehicle has more than two drivers the RKE transmitter recall of memory features can be disabled. This is a customer programmable feature of the Electronic Vehicle Information Center (EVIC) set through the use of the appropriate steering wheel switches. Refer to Electrical - Message Systems/Message Center/CENTER, Electronic Vehicle Information - Operation for additional information on the customer programmable features. The memory system also has an "Easy Entry and /Exit" feature that provides the driver with more room to enter or exit the vehicle. When the seat is in a memorized position, it will move rearward 55 millimeters or to the end of its travel, whichever occurs first, when the key is removed from the ignition switch lock cylinder. This is also a customer programmable feature of the Electronic Vehicle Information Center (EVIC) set through the use of the appropriate steering wheel switches. The memory system also has a "Tilt in Reverse" feature that tilts the outside mirrors down a fixed, incremental angle when the vehicle is shifted into REVERSE with the ignition switch in the RUN position. This feature provides the customer with a better view of the ground and vehicle in the area of the rear tires when backing up.

 

OPERATION POWER SEAT SYSTEM The power seat system receives battery current through a fuse in the Totally Integrated Power Module (TIPM) so that the power seats remain operational, regardless of the ignition switch position. When a power seat switch is actuated, a battery feed and a ground path are applied through the power seat switch contacts to the appropriate motor or motors. The motor and drive unit operate to move the seat in the selected direction until the switch is released, or until the travel limit of the power seat track is reached. When the switch is moved in the opposite direction, the battery feed and ground path to the motor is reversed through the switch contacts. This causes the motor to run in the opposite direction. MEMORY SEAT SYSTEM The Memory Seat Module (MSM) receives battery current through a circuit breaker in the Totally Integrated 2009 Dodge Grand Caravan SE 2009 ACCESSORIES AND EQUIPMENT Power Seats, Front - Service Information - Grand Caravan, Town & Country steve Monday, May 23, 2011 2:14:04 PM Page 5 © 2006 Mitchell Repair Information Company, LLC. Power Module (TIPM) so that the power seats remain operational, regardless of the ignition switch position. When the driver memory seat switch control knob is actuated, a resistance signal is sent to the MSM via the Controller Area Network (CAN) bus circuit. The MSM is responsible for the 12V battery feed and ground path to the power seat adjuster motor. The adjuster motor operates to move the power seat adjuster mechanism through its drive unit in the selected direction until the switch is released, or until the travel limit of the adjuster is reached. The MSM receives memory set/position switch input through the CAN bus circuit. The MSM also receives hard wired input from the hall effect sensors, mounted on each of the driver power seat adjuster motors and the driver side view mirror motor. The programmed software in the module allows it to know where the seat/mirror is located in its designed travel by a pulse count generated from the hall effect sensors. This way, when the memory switch is depressed the module will power the seat adjuster/mirror motors until the correct preset location is achieved. The module will prevent the seat memory recall function from being initiated, if the transmission gear selector lever is not in the Park position, or if the vehicle is moving. These inputs are monitored over the Controller Area Network (CAN) bus circuit by the MSM. 

 

I will e-mail it if you want... is a lot in that one... 38 pages but no schematic.

[Taffy]

Thank you for your offer. I will PM you my email address. I'd like to get this thing sorted. It almost failed the MOT this year because the seat couldn't be adjusted correctly.

[SpAwNtoHell]

Looks like the multi way switches if you ask me as memory is only controlled through the module, manual adjusting... not.

[SpAwNtoHell]

This is the schematic so is not actual sensor... just motors the switches... the variable resistance of the motor... is used by the memory sets by module... or i would call it just wiring...

Edited May 22, 2018 by SpAwNtoHell

[Taffy]

I received the pdf's. Thank you very much for those. It's a fair bit of reading
I recognise the schematic you posted though. I have the same disc. It's very handy and worth having. Just a bit of a pain to configure the system so that the wiring diagrams show properly. Got there in the end though.

[SpAwNtoHell]

I found it easy to acces the diagrams really but i have a very strong it background i started with electronics and in it was very easy mechanics now was the hardest to pickup but the previous stuff i done in the past seem to matter a lot. Let me know how you get on with the seats, my chrysler end it having a date with the dealership and after they fidled with it for a month they replaced the gearbox, not sure if is recon or new but for sure looks very shiny in there... and now... for some reason the seat works every time, i can see someone went in there to the switches... ( i was planning to adress the issue with the seats and another thing with the central locking on one of the sliding doors myself but they done the seat..) so what i was thought is switches related... i think this proved it.

[Taffy]

I don't think your problem was quite the same as mine. I also have an electronics background. I have already swapped out the switches but it made no difference. I haven't been able to obtain a seat module so am unable to check that.  I am still hoping to get one, even to borrow just to prove the point. My final idea is to fit a new changeover switch directly to the forward/backward motor, but I would then lose the memory function.

[SpAwNtoHell]

Can you acces with your diagnostic your seats control module?

[Taffy]

Unfortunately no. My reader is just a basic "one size fits all" and not geared towards any particular brand.

[SpAwNtoHell]

not sure if is to late but... you have a seat position sensor part number is 5084008AA pm me  to confirm... 

 

ps: i just fixed my crystal ball

[Taffy]

Fixed it!

 

I finally got my seat working properly again. I had already eliminated the switches as the cause, leaving only the seat module or (so I believed) the position sensor. Today I finally got an opportunity to remove the seat module. A replacement module would have fixed the problem, but I didn't have one to try, so I decided to see if I could find anything wrong with this one. It came apart easily enough and I was able to get at the circuit board. I began by unsoldering all the connectors and relays, then soldering them up again, just to make sure there were no dry joints. Then I noticed the pins of the power connector were slightly bronzed in colour. They were tarnished. I cleaned them with a fibre pencil, reassembled the module and refitted it to the car.

The seat now works perfectly. Result!

[SpAwNtoHell]

Glad you sorted it out. I am still curious where the position sensor is located tho as apparently it is one for each front seat.