r/Jeepwj

Advanced OBD2 diagnostic and module control app for the 1999-2004 Jeep WJ

WJ1850 is a diagnostic and module control application for the 1999–2004 Jeep Grand Cherokee WJ (4.0L and 4.7L gas engines). It connects via an ELM327 Bluetooth OBD2 adapter and communicates with the vehicle over the J1850 VPW PCI bus.

Features:

Live engine data display with gauges and graphs (RPM, speed, coolant, voltage, fuel level, and more)

Dashboard view with passive bus sniffing for real-time data without active polling

Fault code reading and clearing, with built-in reference for 815 WJ-specific DTC definitions

VIN retrieval and module information

Module actuations and status reads across 10 vehicle systems:

Anti-Lock Brakes (CAB)

Body Control Module (BCM)

Driver Door Module

Passenger Door Module

Automatic Temperature Control (ATC)

Instrument Panel Cluster (IPC)

Sentry Key Immobilizer (SKIM)

Transfer Case Control (XCM)

Memory Seat Module (MSM)

Occupant Restraint Controller (ORC)

Wheels and Tires tab with individual wheel speed monitoring and tire pressure display

Raw bus tools for advanced users — custom frame composition, command logging, and live bus monitoring, ad-free, no data collection

Known Limitations:

WJ1850 operates exclusively on the J1850 VPW PCI bus. It does not communicate over the SCI bus and therefore cannot perform any functions that require SCI access, including:

PCM (Powertrain Control Module) bidirectional functions, flashing, or proprietary parameter access beyond standard OBD2 Mode 01 PIDs

TCM (Transmission Control Module) direct access, adaptive resets, or solenoid actuations

PCM/TCM-specific live data streams beyond what is exposed through standard OBD2

Standard OBD2 Mode 01 live data (RPM, vehicle speed, coolant temperature, etc.) is fully supported via the PCI bus.

Requirements:

WJ1850 requires an ELM327 Bluetooth adapter that supports the SAE J1850 VPW protocol. Most low-cost generic adapters do not properly support J1850 VPW — a quality adapter is recommended for reliable operation.

Recommended adapter: ELM327 OBD2 V1.5 Bluetooth 4.0 (PIC18F25K80 chipset).

This application is not affiliated with or endorsed by Chrysler, FCA, Stellantis, or Jeep.

Reminder this app is written for 1999-2004 WJ. No warranty

Rolled the windows down on my poor car, too hot to take a damn picture.

Dashboard was 217° ..more than enough to boil water.

..at what point does a car interior start to melt?

[deleted]

Hey r/GrandCherokee! First post here — long time lurker, finally joining the family 🤙

I'm Michał, 44 years old, from Poland. Four years ago I bought my dream car — a 2004 Jeep Grand Cherokee WJ, 4.0L I6, automatic, currently RWD only, with an LPG conversion. 155,000 miles on the clock. She's not perfect, but she's mine and I love her.

Here's my situation: I want to do a full restoration and proper build — engine rebuild (yeah, I know the 0331 head gasket story...), transmission rebuild, full 4x4 conversion, 5" long-arm lift, blend door fix, ABS repair, new interior, undercoating, full wrap. The works. I want this thing to be my beast for the next 20 years — I just became a dad again at 44 (baby boy!), so I'm building this for the long haul. Maybe he'll drive it one day.

I'm planning to hand it over to a professional workshop here in Poland and crowdfund part of the costs — labor rates here are much lower than in the US, so the budget is realistic.

I'm pretty new to all of this and honestly don't know where to start. A few questions for you guys:

1. Are there any WJ-specific forums, websites or communities you'd recommend? I found some but I'm not sure if there's something better for the WJ specifically. Where do the real WJ people hang out?

2. For the crowdfunding side — has anyone here ever done something like that for a build? Is it even realistic? I have no idea how to get people interested or where to post it. Also — one thing I'm struggling with is finding a platform that actually works for withdrawals in Poland. GoFundMe doesn't support Poland at all. After a lot of googling I ended up on something called 4fund.com — anyone heard of it? Is it legit? I'm a bit lost here honestly.

3. Random one — my WJ originally came from the US. Is there any way to trace the first owner using the VIN? Would love to know where she came from before ending up in Poland.

Dropping some photos below. Be kind — she needs work, but she has good bones 😄

Thanks for having me. Happy to be part of this community.

— Michał

https://youtu.be/2gXHA7sWfBg?is=oHIpSTkiUrSR7luX

What information do i have on hand for my references?

Including a good bit of the pre-2004drb3 , ..& 60 models, 312 year|model combinations, 2004-2017.

Jeep: Wrangler JK (2007-17), Grand Cherokee WK1 (2005-10), Grand Cherokee WK2 (2011: 17), Cherokee KL (2014-17), Compass (2008-17), Patriot (2007-17), Liberty KJKK (2006-15), Commander (2006-10), Wrangler military/export (2008-17)

Ram: 1500 in multiple body variants (2006-17), 2500/3500 HD (2010-17). ProMaster/ProMaster CIty (2015-17)

Dodge: Charger (2008-17), Challenger (2008-17), Durango/Aspen (2004-09), Dakota (2005- 12), Caliber (2007-14), Nitro (2007-12), Dart (2013-17), Viper (2007-17)

Chrysler: 300C/Charger/Magnum LX platform (2005-17), PT Cruiser (2006-10), Sebring Convertible (2007-08), Crossfire (2007-12), Pacifica (2017), Grand Caravan/Town & Country (2008-17)

Who else out there has a dashboard running 60 frames a second :)

Ok now it’s officially the cleanest WJ in Iraq

Unfortunately I cant keep up with rust, pretty much needs rear frame stiff ners and rockers and a few small patches here and there to get her mostly fixed up along with motor mounts and a few other things. I just cant keep up and rather not let her die. Spending time with the kids and family leaves this on the back burner too much. Strong 4.0, She has regeared axles (4.88) with lockers front and rear, Dana 44 rear, chromoly front shafts, iron rock 6.5" long arm front and short arm rear lift, upgraded rear sway bar, quick disconnects, custom front and rear drives shafts, slip yoke eliminator, I just put on brand new 35" nitro trail grapplers, new fuel pump, new injectors, trans was replaced 5 years ago with maybe 20k-30k miles on it, massive upgraded trans cooler, new magnaflow cats, rear tire carrier ( yes it opens up and stays open without issue ) trail forged HD otk hiem joint steering, 2 working keys and fobs, all new knuckle ball joints, new front timkin wheel bearings, new brake calipers and brake rotors all the way around, bilstien shocks, tower spring guid cones, spring retainers, android auto factory style radio, new rear axle bearings and seals, new headlights, transfer case skid plate. I have a rear axle truss, front radiator guard that needs installed but will go along with it. I also have a brand new in the box Eton style twin screw plug and play super charger from boosted technologies that will go along with it. If anyone is interested let me know, id like someone that will actually enjoy it and bring it back to life to end up with it. Im located in Pennsylvania, send me a message for more details and price.

Edit: I wasnt sure if It was allowed for me to post prices and sell it like that or not that why I said message, I was asking 5k for everything. I think its a fair price considering the supercharger is 4k, tires I have receipts for with the date I got them and price 1500, and it even has a legit inspection done recently.

Does anybody have any advice for getting this support seal off? It's just an access issue. I used a 7/16 3/8th socket for the the rest of the pan, but swapped over to a 1/4" 11mm for this final bolt (I left a few support bolts in to hold the pan).

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An "easy" pan replacement job has had a few hiccups. One side was easy, but I fought the other side for quite a while.

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Apparently this thing cannot be replaced easily so I'm trying hard not to break it. Thanks in advance!

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In an effort to be clear, the bolt on the passenger side came off fairly easily. The seal moved enough to allow access. The driver's side is being a PITA.