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Old 26th September 2023, 17:30   #31
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Re: Maruti Jimny Review

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Originally Posted by purohitanuj View Post
The brake pedal just dint move.
Can you please confirm if you can see a 'vacuum reservoir' in your Jimny. A kind of small spherical reservoir in the vacuum circuit, used as a compensator during such event or low engine rpms/start ups.

Its really a nerve recking finding. Imagine you loose your brakes in your AT, there is nothing you can do there. In MT atleast you have something like gear level in your rescue to reduce the degree of damage.
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Old 26th September 2023, 17:48   #32
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Re: Maruti Jimny Review

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Originally Posted by UD17 View Post
Can you please confirm if you can see a 'vacuum reservoir' in your Jimny. A kind of small spherical reservoir in the vacuum circuit, used as a compensator during such event or low engine rpms/start ups.

Its really a nerve recking finding. Imagine you loose your brakes in your AT, there is nothing you can do there. In MT atleast you have something like gear level in your rescue to reduce the degree of damage.
I have gone through the service manual and it seems that there is no "reservoir" . I know that cars do have reservoir for 1 brake post engine is switched off apart from the continuous support it gives to the system .
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Old 26th September 2023, 18:54   #33
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Re: Maruti Jimny AT | Brakes not functioning at low rpm at high altitudes

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Originally Posted by purohitanuj View Post
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.
Sorry if i missed your response but did you raise this to Maruti A.S.S.? If yes, what is their say on this?
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Old 26th September 2023, 19:19   #34
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Re: Maruti Jimny AT | Brakes not functioning at low rpm at high altitudes

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Sorry if i missed your response but did you raise this to Maruti A.S.S.? If yes, what is their say on this?
No as of now as the brakes are absolutely fine. How would they sense and work upon?
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Old 26th September 2023, 19:37   #35
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Re: Maruti Jimny AT | Brakes not functioning at low rpm at high altitudes

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Originally Posted by purohitanuj View Post
No as of now as the brakes are absolutely fine. How would they sense and work upon?
Isn't that their problem to figure out. You can provide them the evidence you have for non functional brakes. They should provide an answer to the same. I know raising it on the forum creates awareness but it will not create a fix.

And the issue that you explained is outright scary and requires a fix from Maruti.
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Old 26th September 2023, 22:41   #36
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Re: Maruti Jimny AT | Brakes not functioning at low rpm at high altitudes

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Originally Posted by ferrarirules View Post
Isn't that their problem to figure out. You can provide them the evidence you have for non functional brakes. They should provide an answer to the same. I know raising it on the forum creates awareness but it will not create a fix.

And the issue that you explained is outright scary and requires a fix from Maruti.
It will probably be a collective effort. I've already tweeted, going to send an email and post on Facebook. I am hoping that TBHPians connected to the automotive industry who read this thread may help getting the issue out to MS executives. Lets see how it pans out but the genie is out of the bottle now and all thanks to Anuj and his troop for documenting this.
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Old 27th September 2023, 01:07   #37
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Re: Maruti Jimny AT | Brakes not functioning at low rpm at high altitudes

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Originally Posted by purohitanuj View Post

Just returned from an Umlingla trip with the SimplyJimny group (with 10 Jimny's).

This same issue recurred with all Jimnys over the next couple of days.

At high altitudes, the brake booster fails to generate sufficient boost for the brake system at idling or lower RPMs.
Have you fitted a Throttle Controller on your Jimny? How many of the 10 Jimnys in your group have a Throttle Controller installed?

Being a drive to a remote location with few or no petrol pumps in the vicinity - how many of the 10 Jimnys had set the Throttle Controller to Economy mode to save fuel?

I am asking these questions - because clearly there seems to be an issue with the engine running at low RPMs and consequently vacuum assisted brakes and vacuum assisted front hubs not functioning properly.

And that's precisely what one should expect if one sets the Throttle Controller to Economy mode. The RPMs would drop to rather low values. This would cause deficient vacuum building in the brakes and front hub.

I also wonder, if after reaching back on the plains - whether you set the Throttle Controller back to some higher performance mode, whereby the engine RPMs would be higher. Naturally, due to the higher engine RPMs, you wont face the braking issue or front hub engagement issues thereafter.

.
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Old 27th September 2023, 07:19   #38
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Re: Maruti Jimny AT | Brakes not functioning at low rpm at high altitudes

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Have you fitted a Throttle Controller on your Jimny? How many of the 10 Jimnys in your group have a Throttle Controller installed?

Being a drive to a remote location with few or no petrol pumps in the vicinity - how many of the 10 Jimnys had set the Throttle Controller to Economy mode to save fuel?

I am asking these questions - because clearly there seems to be an issue with the engine running at low RPMs and consequently vacuum assisted brakes and vacuum assisted front hubs not functioning properly.

And that's precisely what one should expect if one sets the Throttle Controller to Economy mode. The RPMs would drop to rather low values. This would cause deficient vacuum building in the brakes and front hub.

I also wonder, if after reaching back on the plains - whether you set the Throttle Controller back to some higher performance mode, whereby the engine RPMs would be higher. Naturally, due to the higher engine RPMs, you wont face the braking issue or front hub engagement issues thereafter.

.
Only 2-3 Jims had throttle control. Mine didnít had one. The Jimnys gave fantastic fuel efficiency (11-12km/l in those terrains). I was able to drive from Hanle to Manali with 2 bars left in which I did many offroad shortcuts twice ( same shortcut - decent and ascent ). I dont think throttle controller can summon a lower gear or holding gear to gearbox. The Jimny would still coast on downhill slope leading to drop in rpms.
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Old 27th September 2023, 10:55   #39
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Re: Maruti Jimny AT | Brakes not functioning at low rpm at high altitudes

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Originally Posted by Cresterk View Post
It's bad enough that Maruti Suzuki cheaps out on metal quality and structural integrity when making cars. Looks like the lack of any consequences has emboldened them to cheap out on brakes too. Does anyone know if this is a common issue on International spec Jimnys as well or limited to India?
Extremely important point. I hope you've all seen the video of the Jimny car crash where the cabin peeled off when it hit a Bolero CV. Very scary
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Old 27th September 2023, 11:44   #40
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Re: Maruti Jimny AT | Brakes not functioning at low rpm at high altitudes



This is the first time I noticed this issue at Jispa morning.

This is the 1st encounter of degraded brake issue at Jispa. We stayed overnight at Jispa and in the morning, I started my AT Alpha Jimny and put it in D without any throttle input. It crawled forward , and when I tried to stop, the brake pedal was rock hard. I tried reverse and the same thing happened. Then I popped open the hood to check the oil ( which was fine ) and also noticed the disc pads (which were dry). I then asked Manik to give it a try and how he feels about it. He also noticed pedal being hard and very poor brakes.

Last edited by purohitanuj : 27th September 2023 at 11:48.
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Old 27th September 2023, 12:08   #41
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Re: Maruti Jimny AT | Brakes not functioning at low rpm at high altitudes

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Originally Posted by Clouseau View Post
Extremely important point. I hope you've all seen the video of the Jimny car crash where the cabin peeled off when it hit a Bolero CV. Very scary
Guys, one earnest request. Kindly report all initial niggles and problems faced by owners/ users to MSIL regional service escalation matrix, NEXAexperince and to the highest level of MSIL if not resolved properly or within a reasonable time frame. Let's not remain stuck in that deadly accident and its post mortem alone. There is no point in endless debate on bad build quality, cost cutting of Maruti Suzuki cars. We shouldn't have bought Jimny if we were concerned about bad build and interior quality, inferior cars, unsafe cars, underpower cars, cost cutting etc. those are now USP of MSIL cars.

I have reported the initial niggles faced in my Jimny, escalated it through proper channel and those got resolved within a reasonable time. After the escalations, things moved fast. All hurdles and lack of training of MSIL service staff were reported in that initial niggles thread.

The problem statements must be clear and to the point, with supporting details like sequence of events, time, other conditions like environmental conditions, altitude etc. and evidences (like audio visual files, photographs, sound recording, video clips etc), our trial and error or corrective actions so that MSIL engineers and R&D can clearly understand the problem correctly and provide permanent solution or recalls.

Last edited by RijuC : 27th September 2023 at 12:10.
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Old 27th September 2023, 12:24   #42
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Re: Maruti Jimny AT | Brakes not functioning at low rpm at high altitudes

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Originally Posted by purohitanuj View Post
The ABS motor did kick twice ( on different days ) when I just touched the brakes ( didn't press a bit; just touched) . The road condition was clear with no reason for ABS to kick in. It went away in 1-2 seconds. Felt like ABS is confused. It happened at very low speeds, below 20 km/hr for sure. Dont know what ever that means, but it could help people analyzing the issue.
The Jimny has a vacuum sensor on the brake booster and sometimes, via the 'Hydraulic Brake Boost' function, ESP can compensate and build hydraulic pressure at the wheel.

By the description of your issue, since it is an NA engine without a vaccuum pump, the only solution is to keep the engine at higher rpms as continuous use of the brakes at low rpm will consume the vacuum and it can't refill at the same rate of use unless the engine is spinning at higher rpms.
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Old 27th September 2023, 13:10   #43
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Re: Maruti Jimny AT | Brakes not functioning at low rpm at high altitudes

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Originally Posted by fiat_tarun View Post
The Jimny has a vacuum sensor on the brake booster and sometimes, via the 'Hydraulic Brake Boost' function, ESP can compensate and build hydraulic pressure at the wheel.

By the description of your issue, since it is an NA engine without a vaccuum pump, the only solution is to keep the engine at higher rpms as continuous use of the brakes at low rpm will consume the vacuum and it can't refill at the same rate of use unless the engine is spinning at higher rpms.
Good point. My guess is that hydraulic brake assist function of ABS unit will only activate after a certain speed - even if it does the brake pedal will feel the same as the brake booster is vacuum suspended.

If you look at the video and discription, the brake pedal behaves similar to engine being off as soon as he moves , there is no repeated braking ag all, something is blocking the pipe between intake manifold and booster when it's cold.
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Old 27th September 2023, 14:18   #44
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Re: Maruti Jimny AT | Brakes not functioning at low rpm at high altitudes

Hi. I drive a MT and I too returned from a drive up to Umling La earlier in September. Our party consisted of a Thar petrol MT and a ScorpioN 4Explor and my Jimny.
I first noticed this terrifying loss of brakes somewhere just after we started from Hanle, towards U Top. It happened at a hairpin and since the NA Jimny was already struggling to keep up with the turbo Mahindra’s at that altitude (the engine would lose all power if allowed to slip below 2300 RPM, and the car would only roar upwards in 1st, till the road somewhat flattened out), and I was gunning for all it was worth to not stall. Naturally, a fair amount of speed was being carried into the corners and suddenly I discovered - no brakes! The pedal just sank under my foot and the car hurtled on, right into the tail of the Thar. Fortunately, there was just enough wiggle room for me to yank the Jimny out of the collision line and we averted an accident.
Initially ascribed this to overheated brakes from enthusiastic driving, but things didn’t improve even on the way back and the brakes remained ‘spongy’ at best.
Only after we descended past Manali did life get back to normal and once I put it in service back in NCR, I noticed that the tech attending my car, needed to top up brake fluid by a healthy margin. As expected, they had no answer when I asked them about this peculiar behaviour. Neither the Thar or the ScorpioN complained of brake problems, although, they had their own gremlins to fight.
A quick google search throws up a lot of theories about why brake fade happened at altitude, and I’d have accepted this until I read this as a fairly widespread occurrence in Jimny’s. MSIL have a problem on their hands for sure.

Last edited by SUVolens : 27th September 2023 at 14:21.
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Old 27th September 2023, 15:00   #45
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Re: Maruti Jimny AT | Brakes not functioning at low rpm at high altitudes

https://www.cartoq.com/multiple-maru...ates-incident/

CarToq reference to this article.
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