EDIT: the problem was traced by Chandlers of Belton to a Steering Sensor Failure.
My vehicle experienced the following Fault Messages:
- Reduced Braking Performance
- UpHill Assist Not Available
- TSA not available
- Downhill Assist Not Available
- ESC Not Available
- Power Steering Failure & Windscreen Wipers
Then today:
- Diesel heater symbol – which would not cancel. (Eventually RESET with powering down the car for 10 minutes).
On the Grenadier, the diesel pre‑heater / glow‑plug icon is not just about starting; it’s tied into the engine management, CAN‑bus, and voltage stability. When it stays on unexpectedly, it’s almost always a symptom of an electrical or communication dropout, not a genuine heater fault.
What the stuck diesel heater symbol tells us: The glow‑plug / diesel heater icon staying illuminated means the following:
The ECU didn’t complete its startup sequence: If voltage dips or a module doesn’t initialise, the ECU keeps the heater cycle “open” because it thinks the engine is still in pre‑start conditions.
CAN‑bus messages between the engine ECU and body control module were interrupted. When the CAN‑bus drops out, the ECU can’t confirm the heater cycle has ended, so the symbol stays on.
This is the same network that carries:
- ESC
- Uphill/Downhill Assist
- Trailer Stability Assist
- Brake system messages
- Power steering control
- Wiper control
This is classic Grenadier CAN‑bus instability, almost always triggered by low voltage or a poor connection.
Most likely root cause (in order of probability) on Early Build Grenadiers :
1. Loose or under‑torqued earth strap (very common on sub‑1500 builds). The main chassis earth strap on early Grenadiers was often not torqued correctly at the factory. A poor earth = unstable voltage = CAN‑bus chaos.
2. Battery quality issues on early builds. The first batches had batteries that were:
- Slightly undersized
- Prone to voltage sag in cold weather
- Sensitive to short‑trip use
A momentary voltage dip during ECU wake‑up can trigger every single warning you saw. The diesel heater symbol staying on is a classic sign the ECU didn’t complete its startup handshake.
3. ABS/ESC module moisture vulnerability
Early builds had a connector seal that wasn’t perfect. Moisture or condensation can cause intermittent CAN‑bus dropouts. When the ABS/ESC module drops off the network, you lose:
- ESC
- Hill assist
- Trailer stability
- Downhill assist
- Brake system messaging
4. Steering angle sensor dropout. Another early‑build quirk. If the steering angle sensor loses communication, the vehicle throws:
- ESC unavailable
- Hill assist unavailable
- Reduced braking performance
