My Maruti Jimny AT: Facing brake issues at low rpms at high altitudes

I attempted to force the brake pedal down with full strength while in neutral, revving the engine.

BHPian purohitanuj recently shared this with other enthusiasts.

Just returned from an Umlingla trip with the SimplyJimny group (with 10 Jimny's) and I need to share some crucial findings with a timeline.

During my stop in Jispa, I attempted to move my Jimny (Alpha AT) the next morning, but was met with a startling discovery: Zero braking! The brake pedal felt rock solid and wouldn't budge. After checking the brake fluid (which was at proper levels), I grew concerned. I asked Manik to give it a try, and he too was taken aback by the brakes, remarking, 'It feels like trying to tow a dead car.'

I attempted to force the brake pedal down with full strength while in neutral, revving the engine ( The brake pedal moved in much further on revving) . Finally, I got some braking action. The parking brake, however, functioned normally.

Concerned about my Jimny, we decided to address the brake issue and have them checked and bled in Leh. I was instructed to trail the convoy.

Upon reaching Shinkula top, I realized my brakes were non-existent! I ceased using the parking brake and once again revved the engine to regain some braking power. Additionally, I observed the ABS motor engaging when I lightly rested my foot on the brake pedal without applying pressure.

This same issue recurred with all Jimnys over the next couple of days. I encountered numerous local Jimny owners who experienced identical problems on this trip.

After some driving and analysis, here's my assessment:

At high altitudes, the brake booster fails to generate sufficient boost for the brake system at idling or lower RPMs.

This is particularly critical in AT mode, as in 'D' mode, when the car descends a slope, the AT shifts to the highest gear ( or coasts) , causing a drop in RPMs akin to idle conditions. Within this RPM range, the brake booster struggles to provide adequate boost. This predicament arises when attempting to brake for a hairpin bend, leaving little time for corrective action.

Hence, I strongly implore Maruti Suzuki to conduct thorough testing on high-altitude passes and address this issue. I personally experienced two near misses due to this very problem.

Following my analysis, everyone opted to drive in either 'L' or '2' to maintain higher engine revs throughout the trip. Upon returning to lower altitudes, the problem vanished as if it never occurred. In a manual transmission, one typically operates in a lower gear, resulting in higher engine RPMs. Consequently, this issue is either non-existent or not as severe.

Furthermore, at higher altitudes, 4H/L struggles to engage the front hubs (vacuum assisted), with the 4x4 indicator continuously blinking. To circumvent this, I shifted the car into neutral in 2H and revved the engine to 3K from idle and then back to idle. While repeating this process, I pulled the transfer case lever back for 4H, and it locked within 1-2 seconds (solid green light). Once engaged, it remained locked regardless of engine RPMs. Some of us took shortcuts and nearly all managed on 2L as the hubs failed to lock, but the transfer case shifted into crawl ratio.

It appears that the very purpose of owning a Jimny is being undermined. Brakes failing and 4x4 hubs refusing to lock in high-altitude regions present a life-threatening issue. I fervently urge Maruti Suzuki to address these concerns before any lives are put in jeopardy.

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