Noob 4WD: Locked Center Diff but only one wheel spinning in snow – Is this normal?

[VirtualJSK]

A.I. did an awesome job helping me understand why I got stuck in a snow bank, and I'm reposting so other inexperienced new Grenadier owners know what to expect...

Q: I have a 2025 Ineos Grenadier Fieldmaster without the optional front and rear lockers. Yesterday, I got stuck on a snowbank. I had the center differential locked, so I expected power to be distributed 50/50 to the front and rear axles—meaning at least one front wheel and one rear wheel should spin if I lost traction. However, only one front wheel was spinning. Is my center diff not engaging, or is this expected behavior?

A: This is actually expected behavior for a Grenadier equipped with open front and rear differentials. Here is the technical breakdown of why that happens:

1. The Center Lock vs. Axle Diffs​

The Grenadier’s center differential lock (the Tremec unit) ensures that the front and rear driveshafts spin at the same speed. It guarantees a 50/50 power split between the two axles. However, it does not control how power is distributed across the individual wheels on those axles.

2. The "Path of Least Resistance"​

Because the Fieldmaster (without the Trialmaster's Rough Pack) uses Open Differentials on the front and rear axles, torque always follows the path of least resistance.

• If your front-left wheel is on ice and the front-right is on pavement, the open diff sends 100% of the front-axle power to the spinning wheel on ice.
• The same logic applies to the rear. If the rear wheels have significantly more resistance (buried in deep snow) than the spinning front wheel, you may not see them move at all, even though they are technically "receiving" 50% of the engine's torque.

3. Why didn't Traction Control (ETC) help?​

The Grenadier uses Electronic Traction Control (ETC) to brake a spinning wheel, which "tricks" the open diff into sending power to the wheel with grip. However:

• Throttle Input: ETC often requires steady, sustained throttle to activate. If you "blip" the throttle or let off as soon as you see a spin, the system won't have time to intervene.
• Off-Road Mode: You must be in "Off-Road Mode" for the most aggressive traction control logic.
• Total Resistance: In deep snow or if the vehicle is high-centered, the braking force of the ETC might not be enough to overcome the massive resistance of the snow holding the other wheels in place.

Summary: Your center diff was likely working perfectly. Without mechanical front/rear lockers, you are relying on the ABS system to manage cross-axle traction. In high-resistance situations like a snowbank, an open-diff vehicle can still "one-wheel peel" if the traction control doesn't get enough consistent throttle to bite.

---

Quick Tips for Next Time:​

1. Engage Early: Lock the center diff before you enter the obstacle.
2. Off-Road Mode: Ensure it's active so the ETC knows you're in low-grip conditions.
3. Steady Maintenance Throttle: Give the computer a second or two of steady RPMs to allow the brakes to find traction on the stationary wheels.

 

[Blackwolf]

Typical AI-generated guff which doesn't answer your question.

If you have no axle difflocks, a locked centre diff and only one wheel on only one axle is spinning then something is wrong. Either the centre diff isn't actually locked (most likely) or the diif is locked but something has broken, such as a halfshaft, in the axle without the spinning wheel. If the latter you'll have no drive at all with the diff unlocked.

 

[Baron von Teuchter]

Typical AI-generated guff which doesn't answer your question.

If you have no axle difflocks, a locked centre diff and only one wheel on only one axle is spinning then something is wrong. Either the centre diff isn't actually locked (most likely) or the diif is locked but something has broken, such as a halfshaft, in the axle without the spinning wheel. If the latter you'll have no drive at all with the diff unlocked.

Yeah that didn’t make sense to me.

With CDL locked if the vehicle isn’t moving you should see two wheels (one front and one rear) spinning power away surely?

 

[Glen]

Ineos promotional material has a brief description of ETC and their 2023 spec sheet lists ETC, but this term does not appear in the Owner's Manual or anywhere I can find in the online Workshop Manual and related documents. I suspect the use of the term "ETC" is a marketing device that really refers to the function of the ESC system and not to replacing the function of a limited-slip or locked differential.

If all mechanical systems were functioning as intended and you had no traction force with the center differential locked, then at least one tire on each axle (with open diffs) had insufficient traction to move the vehicle. Your observation that "only one front wheel was spinning" is likely incorrect.

Remember that AI is "artificial," but it is in no way "intelligence," it's a Large Language Model. AI is infamous for presenting falsehoods.

 

[VirtualJSK]

When you say my observation was incorrect, I understand... You are probably guessing that I could not tell how many wheels were spinning from inside of the car. In this case, however, two friends were with me and trying to help me get out of the snow bank, and from outside of the car they observed that only the right front wheel was spinning. I'm back to wondering whether the center differential actually locked. I did not try to actuate the center diff until after I was stuck. Maybe it never clicked in. Are you certain that there are no circumstances (other than the significant mechanical issues you mention) where only one wheel would spin when the center diff is locked?