OBD-II Live Data Display - Scangauge / Ultragauge (1996-2001)

Difficulty 1/50.25–1 hrs$30–2001996, 1997-2001

Scangauge II ($170) or Ultragauge ($80) plugs into the OBD-II port and displays live PCM data — coolant temp, trans temp (via PCM PID), AFR, voltage, MPG, even trip computer. Great alt to physical gauges on 1996+ XJ.

1996-2001 XJ has OBD-II. The PCM monitors trans temp (via the trans solenoid pack), coolant temp, air intake temp, MAP, MAF (none on stock), short/long term fuel trim, O2 voltages, and timing. All of this is readable via a $20 OBD-II Bluetooth adapter + Torque Pro on Android, or a dedicated unit:

Scangauge II ($170): the standard. Dedicated screen, runs 4 gauges + trip data, X-Gauge custom PIDs let you read trans temp from the PCM directly (PID 195C or similar — varies by year). Reliable and stays in the truck.

Ultragauge EM Plus ($80): similar functionality, larger screen, slightly cheaper. Less polished UI.

Bluetooth OBD2 dongle + Torque Pro on Android phone ($30-50 total): cheapest path, screen-on-demand, can log to SD card.

What to display: trans temp, coolant temp, instant MPG, battery voltage, and clear-codes shortcut. For SOA/heavy use, trans temp from PCM is comparable to a real trans temp gauge if you trust the sender (it's near the solenoid pack, reads pan-ish temp).

Pre-1996 (OBD-I): no OBD-II port, requires AMC/Chrysler-specific scan tool. Scangauge will NOT work. Stick with physical gauges.

Why it works

multiple parameters, one device
trans temp without drilling
OBD-II code reader built in

Trade-offs

1996+ only
X-Gauge setup requires correct PID per year

Tools required

nothing - plugs into OBD port

Parts

Part	Vendor	Est. price
Scangauge II	Linear Logic	~$170
Ultragauge EM Plus	Ultragauge	~$80
OBDLink MX+ Bluetooth dongle	OBD Solutions	~$90

Sources

{'title': 'Scangauge II for XJ Trans Temp', 'url': 'https://www.scangauge.com/products/scangauge-ii'}
{'title': 'Cherokee Forum - X-Gauge PIDs for XJ', 'url': 'https://www.cherokeeforum.com/f2/scangauge-xgauge-codes.html'}

Written and maintained by an AZ wheeler and driveway wrencher. Always cross-reference your factory service manual — modifications affect vehicle safety and warranty. Work at your own risk.