How to Fix 2003 Lincoln Town Getting Park Assist DTC’s with VCM2?


2003 Lincoln Town Car Signature with Park Aid

Interface OHP ELMconfig USB with manual HS//MS switch

Connects successfully in HS mode and I can see DDM,DSM LCM, ATC,ABS, PATS and other modules – but not PAM.



The ISO9141 Protocol has been supported by Both Forscan And ELM327 based adaptors since the beginning versions. HS/MS switch must be in the HS Can position for these early SCP/PWM and ISO equipped Vehicles. MSCan Position will have no connection.

WDS and NGS are the obsolete Ford Diagnostic software and hardware that were replaced by IDS and the VCM and VCM2

Your Lincoln May have a DLC UBP pin 3 but as far as I know the Cars never had a UBP network or anything connected to it as it was mostly used in the Trucks and SUV’s. There would be about 3 to 5 volts positive to Ground if anything is connected to Pin number 3. Another member on this forum had checked his Lincoln and the 3 pin was there but it was dead.

If the PAM module was responding to Forscan through the adaptor, it should have shown up in the ISO network tree along with any other modules that are likely on that same network(The overhead consol display that the PAM warning appears on would have to be on that network) and also appeared in the vehicle configuration list.

If it is not showing up there then you will need to gain access(Remove trim panels and such like. Check manual for module location and connector views) to the display module connector and the PAM module connector to check if the positive voltage is present in the PAM module connector and the ground connection out of the connector has continuity.
Then continuity from the PAM module connector to each of the sensors connectors in rear bumper will be next!

If the module is receiving 12 V+ Power and is grounded( A working module should be showing in the network list with DTC’s if these and ISO wiring are good) and sensor wiring and connectors check out then the module communication wires from the PAM module Connector to the Display’s connector and to the DLC Pin number 7 will be the next to check as the Display gets the PAM signal from the PAM module over the ISO network.

If You say you have Service manual then You are about to make good use of it!
It should have wiring and connector Diagrams and a Pin Point flow chart in it!

If the PAM module is receiving 12V+ and has a ground connection the sensor connections check out(sensors and connectors are prone to moisture and corrosion) and the Display and PAM module’s ISO Connection to No7 DLC Pin all check out then you have a PAM module that has probably died!
It does Happen!

Good luck! Hope this is of some help?



Thanks for the feedback. The manuals are helpful except, in this case a bit confusing. In the Module Comunications Network section it says the PAM is on the UBP network and refers me to the Parking Aid section in the same manual, but in that section it clearly says the PAM is on the ISO 9141 network as I mentioned above. I do see the Restraint Control Module (RCM) show up so I guess I do have access to ISO9141.


As for truck vs car – I have noticed the Panther platform (Crown Vic, Grand Marquis, Town Car) seems to “borrow” a lot of components from the truck lines, esp. Explorer. Maybe it’s the similarities in construction and drive line.



You are not alone in the confusion you are experiencing! I ran into this same predicament with my 03 Expedition. The Wiring manual I have shows the PAM in Module communications on the UBP (Violet Wire) network but Forscan reads it on the ISO(Light Blue/White wire) network and the Service manual says PAM is on the UBP network.

It seems that even Ford is confused about this!

If your TC has Climate Controlled Seats and you are not seeing them on the network list they may also be on the UPB network as are mine in the Expy.

If Pin 3 shows any voltage(5 V+ Key on in my Expy) to ground (Pin 4 or 5 in the DLC) you may have a UPB network and PAM may be on it in this case and that is only available with A VCM2 in Forscan. Never have tried with anything else except VCX Nano and that was an exercise in futility. Never got it to connect at all to either of these “Old Guys”! Had to go for a VCM2 Clone (Used it to help the team get UBP support working back in Version 2.3.09) and it has been good so far! Getting hard to find a good one of those unfortunately.

Only other way to tell, and you may be going in there in any case, is to to gain access to the PAM Module connector and see what wire colours are going into the Module Communications pin. Violet likely means UBP, Light Blue/White means ISO, at least it is in the two trucks (03 Expy and 05 F150) I have here, but your TC wiring Diagram may differ!



Yea “FORD Engineered” is sometimes a complement and sometimes a curse.. 🙂 … I love my keyless entry but the idiot who decided the rear axle didn’t need a separate wheel bearing race….. 👿

I do have heated seats and there is a module/controller – have not looked to see what bus it is on. Wish it had “cooled” seats too – that would be a nice feature here in AL – but it did come with a nice window tint job and with the light interior they don’t get too hot.



Correctly installed and updated the Nano connected and read completely fine on the 2010 Fusion although I never tried any configuration changes with it!


If you Do a Search for VCM2 on, you will get a link  and it is the most recommended(close to the original) two PC board version, the Site says it is the same in function as SP177-C and C1. Some on the MHH forum are recommending the SP177-C3; some are steering people to VXDIAG SVCI J2534 passthru devices.


Something I’d also look twice at is the partial(what does partial support mean???) J2534-2 support as that is what allows MSCAN to communicate over Pass thru devices and the “no support for serial cars like F150 F250 F350 F450”.

I am not sure what they mean by “serial cars” unless they mean the UART Based Protocol (UBP) which is a sort of off shoot or maybe a borrowed part of the old and obsolete UART(universal asynchronous receiver-transmitter) protocol DB9 and DB25/26 Pin serial connection( the cable end connecting the VCM2 to the DLC connector is a DB26 pin serial connector) that computers used to use for connecting Modems and early mice, key boards and printers(had a computer way back in the early 2000’s that had a DB9 connected serial mouse and I still have a DB9 serial connected external Fax Modem)(computer mother boards don’t even include the circuit and hardware anymore).


All this may be moot if there is no voltage reading, either with Key on or off at DLC pin 3!


Hope it helps!


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