2.9.2 HDX Dashboard Cluster¶
Type: Analog/Digital Hybrid Instrument Cluster
Model: HDX-96J-TJ (1996-03 Jeep TJ, Black Background)
Manufacturer: Dakota Digital
Product Page: HDX-96J-TJ Instrument System
Overview¶
Drop-in replacement for factory TJ gauge cluster. Combines analog gauges with digital message centers for comprehensive vehicle monitoring.
Mounting: Factory TJ dash gauge location (direct bolt-in)
Background: Black or silver alloy (select at purchase)
Analog Gauges¶
| Gauge | Range | Function |
|---|---|---|
| Speedometer | 0-160 MPH | GPS-based (via GPS-50-2 BIM module) |
| Tachometer | 0-8,000 RPM | J1939 CAN from Cummins R2.8 ECM |
| Oil Pressure | 0-80 psi | J1939 CAN from ECM or included sender |
| Water Temp | 100-260°F | J1939 CAN from ECM or included sender |
| Fuel Level | E-F | Factory TJ fuel sender |
| Voltmeter | 9-17 VDC | Direct battery voltage monitoring |
BIM Modules¶
| Module | Data Provided | Notes |
|---|---|---|
| BIM-01-2-J1939 | Tachometer, oil pressure, coolant temp, check engine light | Cummins R2.8 ECM via J1939 CAN |
| GPS-50-2 | Speedometer (10 updates/sec), compass, altimeter, digital clock | GPS-based, eliminates mechanical speed sensor |
| BIM-22-3 | Tire pressure (4 wheels) | Wireless valve stem sensors |
| BIM-17-2 | Compass (8-direction), outside air temperature | Grille-mounted temperature probe |
Lamps & Indicators¶
| Signal Source | Indicator | Notes |
|---|---|---|
| ECM Harness | Check engine light, wait-to-start | Active low / active high signals |
| CT4 Controller | Turn signals (L/R), high beam, brake | Lighting controller outputs |
| Tail Light Circuit | Dash dimming | Variable voltage dimming control |
| Transfer Case Switch | 4WD/4LO indicators | Transfer case position sensing |
Sensors¶
| Sensor | Range | Mounting | Notes |
|---|---|---|---|
| Factory TJ Fuel Sender | E-F | Fuel tank | Variable resistance sender |
| Oil Pressure Sender (included) | 0-80 psi | Engine block | OR use J1939 data from ECM |
| Water Temp Sender (included) | 100-260°F | Engine block | OR use J1939 data from ECM |
See HDX Control Module wiring table for complete signal routing.
Speedometer Required for Legal Operation
Speedometer is legally required for on-road vehicle operation. GPS-50-2 module provides speed data - ensure GPS antenna has clear sky view for reliable operation.
Outstanding Items¶
🔴 Critical (2)
- Gauge cluster power architecture: PMU OUT9 vs Critical Cabin PDU slots (#144) — Two mutually exclusive power architectures are documented for the Dakota Digital gauge system and must be reconciled before the cluster can be wired:
- Dedicated brushless radiator-fan controller + coolant temp sensor selection (#134) — Moving the GM 84100128 radiator fan off the PMU (OUT2+3+4) onto START-battery-direct power requires a standalone brushless-fan PWM controller with its own coolant temperature sensor, independent of the PMU and the J1939 bus.
High (7)
- iBooster pedal ratio verification against 1.25" booster stroke (#301) — Verify the brake pedal ratio (approximately 4:1 per owner notes, 03-06 TJ/LJ auto pedal) against the Bosch Gen 2 iBooster's 1.25" stroke so the pedal reaches full booster travel without the cylinder bottoming, with the 1-1/8" Wilwood master and Super Duty calipers at all four corners. Bench-measure on assembly.
- Gear position display via J1939 (Turbolamik TCU → BIM-01-2 → HDX) (#110) — Verify that transmission gear position actually reaches the HDX dash over J1939 — and is displayed — without a discrete gear-position sender.
- Brake Proportioning Valve (#60) — Select adjustable proportioning valve for the rear disc circuit (iBooster has no integral proportioning); size on assembly
- Catch Can Mounting Bracket Point (#58) — Select engine bracketry attachment point for Mishimoto MMOCC-UB universal bracket
- AMOT Cable Firewall Grommet (#57) — Assign dedicated firewall grommet for AMOT push-pull cable pass-through (must not share with other cables)
- AMOT T-Handle Mounting Location (#56) — Select dash mounting position for Midwest Control 30-144-TTL-BH-3 (reachable belted, away from accidental contact)
- AMOT-to-Intake Adapters (#55) — Source NPT-to-hose fittings sized to match measured turbo inlet OD
📋 Medium (3)
- Horn button → PMU In 1 wiring path through steering column (#152) — PMU In 1 (horn request) lists "steering wheel button" as its source, and the horn page puts the button on the steering-wheel PTT bracket — but no wire path, gauge, or connector is defined for how the button contact reaches PMU In 1 through/around the steering column. Street-legal item with an under-specified signal path.
- iBooster Wiring Harness Selection (#105) — Select the Bosch iBooster (Gen 2) wiring harness: Tulay's Gen 2 universal (plug-and-play) vs EVcreate Gen 2 connector kit (DIY). Decision pending donor arrival and pigtail condition inspection. Tracked in the purchase tracker but was missing a TBD issue.
- Axle Brake Flex Hose Length (#86) — DOT (FMVSS 106) braided-stainless extended-length flex at each axle - length blocked on axle + suspension selection (Section 10); size to full droop, do not cut until ride height fixed
🔍 Verify (5)
- iBooster standby current spec (ignition-off test value) (#151) — The engine-systems testing checklist includes "Verify iBooster standby current within spec (ignition OFF)" but no standby-current spec value is documented anywhere (the brake-booster page does not state one). The test step cannot be completed as written.
- WAIT-to-start lamp polarity: ECM Pin 35 active-low vs HDX input active-high (#150) — ECM Pin 35 (WAIT lamp, yellow) is active LOW (~0V when WAIT on, ~+12V off); the HDX indicator input is documented as active HIGH. If wired without resolving this, the cold-start indicator reads inverted — and the documented cold-start procedure depends entirely on watching the WAIT lamp.
- Restomod Air HVAC integration — verify A/C request wiring to PMU In 9 + blower draw (#146) — The factory TJ HVAC is replaced by a custom Restomod Air electronic HVAC kit (ordered, owner-confirmed 2026-06-11) — this resolves the original "no A/C request source post-PCM-delete" gap. Restomod Air kits are fully electronic (servo-driven doors, no vacuum), and the control head generates the A/C request: compressor-engage output (12V) → trinary pressure switch (30/406 psi cutouts) → PMU In 9. PMU logic then drives OUT17 → compressor clutch.
- AMOT 4261M 2.8″ intake air-path connection OD / reducer coupler to 2.125″ turbo inlet (#129) — The 4261M02 is a wafer butterfly valve that sleeves into a 2.8″ (71 mm) nominal intake duct; the AMOT datasheet (4261M_Air_Shutoff_Valve_0119rev2) publishes only nominal size (71 mm), bore (61 mm / 2.4″), and overall envelope — not the air-path spigot/wafer OD or clamp interface. The NPT thread in part number
4261M02A027-AA(actuator code 27) is the pneumatic control port, not the air path. - Grid Heater Current (#42) — Design value 80A - verify via element resistance measurement during installation (~0.15 ohm @ 12V).
Build Tasks¶
- Verify oil pressure/temp data available via J1939 from Cummins R2.8
Related Documentation¶
- Dakota Digital System Overview - Complete system architecture
- HDX Control Module - Control box specifications
- BIM-01-2-J1939 - J1939 CAN interface for ECM data
- GPS-50-2 - GPS speedometer module
- BIM-22-3 - TPMS module
- BIM-17-2 - Compass/temp module