KrispyGauge is built for Haltech ECUs — Elite, Nexus and Rebel — and most installs work first time. When one doesn't, the cause is almost always one of a handful of things: power, the ECU type setting, CAN wiring, the Haltech CAN broadcast, or termination. This guide works through them in the order most likely to find the problem, from a blank screen to a keypad button that won't respond.
Start here: the quick checklist
These six checks solve the large majority of problems. Work through them in order:
- Power: red to ignition-switched 12V, black to ground. The gauge should show its boot screen at key-on.
- ECU type: set to Haltech under Settings in the Web UI.
- CAN wiring: yellow to CAN High, green to CAN Low — not swapped.
- Haltech CAN broadcast: turned on in Haltech NSP.
- ECU running: the ECU powered up and in its run state.
- Termination: exactly two 120Ω resistors on the bus, one at each end.
The sections below go through each problem in detail.
The gauge doesn't turn on
If there's no boot screen at all with the ignition on, the problem is power, not CAN.
- Check the 12V feed is ignition-switched and live with the key on. Measure it at the gauge's connector. Don't use a permanent battery feed — the gauge should power on and off with the car.
- Check the ground. Black goes to chassis or ECU ground.
- Check the fuse on the circuit feeding the gauge — and if several gauges share it, that it can carry all of them.
- Check the plug. KrispyGauge uses a 4-pin JST XH connector. Make sure it's fully seated and every wire is crimped into its pin.
Be careful with power. Reversing 12V and ground, a short, or 12V on the CAN H or CAN L pins can permanently damage the gauge and isn't covered by warranty. Check every wire before powering up.
Normal start-up looks like this: the KrispyGauge boot screen shows for about two seconds, the gauge listens for Haltech CAN data, and once it finds it the default gauge face appears showing RPM.
"NO CAN SIGNAL" on the screen
The gauge is powered but isn't receiving Haltech data. Check these in order.
1. ECU type is set to Haltech
Connect to the Web UI, go to Settings and check the ECU type is Haltech. If it isn't, change it — but note that changing the ECU type wipes all your gauge settings, so back up first if you've set anything up.
2. CAN High and CAN Low aren't swapped
This is the most common cause by far. Yellow goes to Haltech CAN High, green to Haltech CAN Low. Check every join between the gauge and the ECU — a swap at one connector is enough to stop everything. If you've repinned the gauge cable into a DTM connector, check the pins against the connector you're plugging into.
3. Haltech CAN broadcast is on
KrispyGauge reads the data your Haltech ECU broadcasts on its CAN bus. In Haltech NSP, check that the CAN broadcast is turned on for the CAN bus the gauge is connected to.
4. The ECU is powered and running
The ECU only broadcasts CAN data when it's powered and in its run state. Make sure the ignition is on and the ECU has started — if in doubt, start the engine.
5. The bus is terminated correctly
A CAN bus needs exactly two 120Ω resistors, one at each end. Most Haltech ECUs terminate their end themselves. KrispyGauge has a 120Ω resistor built in that you can switch on in the Web UI — try without it first, and turn it on if the gauge is the last device on the bus and you still have no signal. The termination resistor guide explains where it's needed.
6. Prove it with KrispyScan
Still nothing? The gauge's built-in KrispyScan CAN analyser shows you exactly what's on the bus. Set its speed to 1 Mbit/s — the speed Haltech uses — and look for traffic.
- Messages showing, including ID
0x360 (the Haltech frame carrying RPM, throttle and MAP), changing as you blip the throttle: the bus is fine and the gauge is receiving data. Go back to the ECU type setting.
- No messages at all: the gauge isn't seeing the bus. The problem is wiring, the broadcast setting, or the ECU not running.
- Messages, but no
0x360: something is on the bus but the Haltech broadcast isn't — check the broadcast setting in NSP and which CAN bus the gauge is wired to.
Readings drop out or flicker
If readings appear and then disappear, come and go, or get worse with a longer cable, the bus is unreliable rather than dead.
- Termination is the usual cause — too few resistors, or too many. Check there are exactly two on the bus. With everything powered off, the resistance between CAN H and CAN L shows how many there are; see the termination guide.
- Connections: a loose pin, a poor crimp or a damaged wire can cause intermittent dropouts. Wiggle-test the connectors with the engine running and watch the gauge.
- Your ECU reporting RX / TX errors in NSP points to the same two causes.
A reading is blank or looks wrong
KrispyGauge shows what your Haltech ECU sends — so most reading problems start in the ECU's setup rather than the gauge.
- A reading stays blank. Check it's one the Haltech broadcast includes on the Haltech supported signals page, and that the matching sensor is set up in NSP. An input that isn't configured in the ECU has nothing to send.
- A pressure reads about −14.7 psi (−1 bar). KrispyGauge shows pressures as gauge pressure: what the ECU reports, minus atmospheric pressure. A reading stuck around −14.7 psi usually means the ECU is sending zero for that channel — check the sensor is set up and calibrated in NSP.
- A reading is there but wrong. Compare it with the same channel live in NSP. If NSP shows the same wrong value, the sensor setup or calibration in the ECU needs fixing; if NSP is right and the gauge isn't, contact us.
- Units: temperatures are in °C and pressures in psi (gauge pressure).
Keypad buttons don't work
KrispyGauge can act as a Haltech 2×4 CAN keypad. If its buttons don't do anything, or only work some of the time:
- Keypad emulation is on on the gauge's Keypad page, as Keypad A or Keypad B.
- NSP is set up for the same keypad: under ECU Settings → CAN Keypad, the matching keypad (A or B) is selected and each button has a function assigned.
- Button actions are Momentary in NSP. Let the gauge handle on/off toggling with Momentary Toggle in its Web UI.
- No duplicate keypad IDs. A physical Haltech keypad or a second KrispyGauge on the same ID interferes — buttons then behave erratically. Each device needs its own ID.
- Buttons work only sometimes with no duplicate IDs? That points back to termination or wiring.
The full setup is in using KrispyGauge as a Haltech CAN keypad.
Problems with two or more gauges
- One works, the other shows NO CAN SIGNAL: check the chain wiring to the second gauge, and that CAN H and CAN L aren't swapped at that join.
- Both drop out now and then: only the last gauge in the chain should have its termination resistor on.
- Keypad buttons misbehave: each gauge emulating a keypad needs a different ID (A or B).
See running multiple KrispyGauges for wiring and setup.
A wideband or EGT module isn't showing
If you have a Haltech WB1/WB2 wideband or a TCA thermocouple amplifier on the same bus:
- Choose the device in the gauge's Settings — WB1, or WB2 device A to D; or your TCA model and box.
- These modules also run at 1 Mbit/s, the same as the Haltech ECU.
- A wideband channel reporting a sensor fault shows blank rather than an old value, so a blank AFR can mean a sensor problem rather than a CAN one.
Setup details: wideband AFR gauge with the WB1/WB2 and per-cylinder EGT with the TCA-8.
You can't connect to change settings
Turn the ignition on, join Krispy_XXXX (password GetKrispy) and type http://4.3.2.1 in full. If it won't connect, the usual culprits are wireless CarPlay or Android Auto taking over your phone, mobile data, or a VPN. All the fixes are in can't connect to your KrispyGauge.
The gauge is stuck or not responding
- Settings in a mess? A factory reset clears them — there's even a way to do it with just the ignition key. Then set the ECU type to Haltech first, and restore your backup.
- Gauge won't start at all, or a firmware update failed? Use USB recovery to reinstall the firmware.
- On old firmware? Keep it up to date — see updating firmware over WiFi, or the bridging update if you're on firmware older than v0.13.
Still stuck?
Email [email protected] or ask in the KrispyGauge Tips & Tricks Facebook group. To help us help you quickly, include:
- Your Haltech ECU model.
- Your gauge's firmware version.
- What the gauge shows, and what you've already checked from this guide.
- A photo of your wiring at the gauge and at the ECU.
- If you can, a short KrispyScan log export of 10–20 seconds.