Understanding the Jimny’s hill hold feature
I’m filing this under common issues as it is a topic of conversation that comes up repeatedly, and it’s useful to understand the feature to get the best out of it.
Sections
Introduction
Generation 4 Jimnys include a ‘hill hold’ feature. In some markets this is noted on the brochures in various forms, e.g. for Australia the following graphic and blurb was included.
Everyone kind of talks about it subtly differently though.
HILL HOLD CONTROL
This feature helps prevent backward rolling even on bumpy and uneven hills, so you can focus on controlling the vehicle’s acceleration.
Suzuki South Africa Brochure
The key here is there is a system that stops you rolling backwards when facing uphill. Cool. Many people don’t even realise their car has it. I (personally) have no problems doing good hill starts with or without using a handbrake, but I do actually gel very nicely with the Jimny’s hill hold feature and it works the best out of many cars I’ve driven with a similar system.
It is important to understand how it works to get the most out of it. There’s also a lot of confusion and mystery about it, since the system is pretty opaque and you can’t turn it off on the road so it’s always there. This leads people to get frustrated with it and/or misunderstand it and how it works.
The owners manual covers this topic from page 3-61 onwards, with the following text
Hill hold control system
The hil hold control system is designed to assist you in starting to move up hills. When you start to move up a hill, the system helps prevent the vehicle from rolling downward (for approximately 2 seconds) while you move your foot from the brake pedal to the accelerator pedal.
The hill hold control system activates for a maximum of about 2 seconds if your foot is
moved from the brake pedal when the following conditions are all met.1) The gearshift lever is in a forward gear or reverse gear.
2) The parking brake is released.
3) The vehicle is on an upward incline.
NOTE:
When the hill hold control system is activated, the following conditions may be found, but this is not a malfunction.
* You may hear a sound from the engine room.
Suzuki Jimny Owners Manual, 2019, pages 3-61 throuh 3-62, owners manual part number 99011-78RB6-01E
* As brake pedal becomes heavy, it may be difficult for you to depress it.
There’s also a number of warnings and further information, including how to disable it, but we’ll get to that shortly.
Ultimately the Jimny is also not hugely smart about what is happening with the car. It doesn’t have a progressive clutch switch to see if you’ve engaged the clutch to the bite point, it just releases when it wants to. Despite what the manual says, the car also does not know if you’re in gear or not in a manual car (it can only tell if you’re in reverse), and, it doesn’t vary the brake pressure to smoothly take up drive: it simply releases the held brake pressure when it wants to.
The brake pressure itself is held by the car’s ABS/ESP pump, which is also how it determines (through the G-sensor) the orientation of the car. Understanding what triggers it but also what releases it is pretty useful to understanding how to make the most of it.
How does it operate?
When the car decides to engage the hill hold function, it does so based on a number of factors. When it engages it, it holds brake pressure in all 4 brake lines via the ABS pump until either a) it releases because it times out after you’ve taken your foot off the brake pedal or b) you take the right actions with the car’s controls to disengage it.
Only works facing up hill (or downhill in reverse)
This is the first and most important characteristic. By design it only works when the car will be travelling up hill. The ‘up hill’ is determined by the ABS unit and it’s G-sensor with the car stopped. With no wheel speed, the car looks at the steady state G-sensor and if the attitude of the car is sufficiently uphill then it will engage the brakes and turn on the hill hold feature.
If the car determines you are in reverse it will engage facing downhill, because you’ll be heading up hill in reverse.
You have to pull up to a stop with the clutch in to allow it to engage
Since the Jimny does not know what gear it is in with a manual transmission, other than reverse, the car does not distinguish between pulling up in neutral or not. However, you do need to come to a stop with the clutch in if you’re in neutral; if the car can see you’ve released the clutch & you come to a stop it will assume you are in neutral since the engine didn’t stall.
You cannot have the handbrake on
Hill hold only works if you use the foot brake alone. If you put the handbrake on then it will not engage and it will expect you to do your own hill start without assistance.
It will release after ~2 seconds after you release the brake pedal
In the absence of any further inputs after taking your foot off the brake, the hill hold system will release the brakes.
The car releases the brake at a certain throttle percentage
The trigger for releasing the hill hold function on the brakes is as simple as
a) come off the brake;
b) apply some throttle.
Even if you are fully on the clutch still, the car will release the brakes as soon as enough throttle is reached. (Really hard to tell what that throttle percentage is; it might be related to the steepness of the hill). If you release the clutch, the hill hold does not release, however. You can actually get the car to totally stall against the brakes if you don’t touch the throttle.
Potentially once the car sees wheels rolling it will release the brakes
Is the clutch pedal position involved?
There are two switches on the Jimny’s clutch pedal. The upper switch is “clutch pedal position switch 2” and the lower switch is “clutch pedal position switch 1”. (CPP for short). CPP1 detects when the clutch is released, and CPP2 detects when the clutch pedal is fully depressed. These switches provide inputs to the ECU: CPP1 is ECU E-42 (purple) and CPP2 is E-17 (green).
One point of confusion for people is if these switches are involved in if the car decides to release the hill hold feature or not, i.e. does it de-activate when you first come off the clutch pedal?
In my testing it appears not. If I do not touch the accelerator but instead come off the clutch pedal then the car will load up against the brakes and start to stall. It will completely stall if I let it, without ever releasing the brakes. You can best see this if you are in neutral and you release the clutch pedal. Since the car doesn’t care if you’re in gear or not, you can pull up and put the clutch in with the transmission in neutral, and the hill hold feature will still engage the brakes.
If you then pull up off the clutch pedal then the car will not move even with the clutch fully released in neutral i.e. the brakes are not disengaged at all by the clutch pedal.
Issues people have had with it
Stalling the car before the brakes are released
As the system relies on throttle percentage to release the brakes, and the car will absolutely let you ride the clutch against the brakes, you need to make sure you have enough throttle on to disengage it. This can feel counter-intuitive but it’s a small engine, so get used to more throttle and faster clutch movements to take up drive if you have this issue.
If you want to learn where the car actually releases for you in relation to how far you push the throttle then go find an empty area with a nice steep hill (e.g. a steep carpark) and let the hill hold engage. While the clutch is fully pressed, come off the brakes and then see how much throttle you need to push to get the brakes to release. So long as there’s nothing behind you nothing bad will happen from this, you’ll just roll back a bit. Go back onto the brakes and come to a stop and practise this a few times to get a muscle memory for what throttle releases it.
When you go to take off and actually want to use the hill hold feature, take up the clutch pedal to the point where it bites and the revs just start to drop. At that point, and only at that point, do you add the throttle amount that releases the hill hold, and then progressively add throttle and release the clutch to smoothly take off.
Car won’t release the brakes at all
This one is perhaps suggestive of other issues happening. It is possible for a brake to stay on if there is some issue in the brake caliper (at the front) or wheel cylinder (at the back). This is especially true for front brakes: sliding calipers are very susceptible to contamination through mud etc and they cease sliding. When the hill hold feature turns off, the brakes might still stay engaged with one pad and this is enough to stop the car rolling nicely and taking up drive.
You can check for this by feeling if one wheel is getting a bit warmer when driving compared to the others (not tyre, the wheel itself, near the centre). That’s a sign of a very tightly dragging brake though. The second check is if the brakes are wearing one pad more than the other, which will happen over time. You’ll also feel the car wanting to pull more in one direction if one side is staying on more than the other which is another diagnostic clue.
In general, I like to pull the wheels off whenever I wash the car after a big 4wd session and will periodically check the brake calipers to make sure they are able to slide on the sliding pins. It’s worth cleaning and re-greasing them quite often if you tackle mud very often, or big water crossings.
Hill hold is engaged on the flat
A few people have reported this but without it happening to me it’s hard to investigate. The most likely suspect for this is the ESP/ABS system needing to be calibrated. The G-sensor is what is used to determine the attitude of the car, so if there’s something meaning that the G-sensor’s perception of level is no longer correctly aligned with the car’s actual attitude then you could have the system holding even on the flat.
In my experience, suspension lifts do not influence this, but it is possible if you ended up with an overly high front end/low rear end that you might fool the car into thinking it’s pointing more uphill than it actually is.
By default, the car runs about 15 mm of ride height higher at the back than the front. Over the 3 door’s wheelbase of 2250 mm, this equates to a nose-down attitude of about 0.4º. That’s what the car is looking for as ‘flat’. If, somehow, you ended up with the front 15 mm above the rear then you’re now nearly 1º different from what the car thinks ‘flat’ is i.e. it will think the car is pointing up a 1º hill on the flat.
If you are having this sort of an issue, you should check the ride heights of the front and rear axles to see if there’s something amiss. I cover how to check that here in how to buy a used Jimny. If it does have roughly a level to a slight nose-down attitude then the next port of call is probably a dealership and ask them to recalibrate the ESP/ABS system, especially the G-sensor and see if that helps.
Clutch engagement mismatch?
Stalling offroad on obstacles
Here’s where the other interesting part from the owners manual comes in that most people don’t realise:
You can disable hill hold in 4L.
You don’t do it through the means you might think, though. You actually disable it by holding down the ESP Off switch for 5 seconds in low range (ESP is already off in low range anyway, so they repurpose the switch!). Note that when you do this you’ll also not have access to the hill descent control for crawling down hills, but if you find you are stalling the car trying to get up obstacles because the brakes are being held then it’s worth trying this.
There is no official way to disable the feature in high range (either 2 or 4WD), however. Some people have held the brake pedal switch down permanently as the car will then use the brake pressure readings to activate the brake lights & it will disable hill hold while it can’t rely on the brake pedal switch.
I wouldn’t necessarily recommend doing this, however. I actually think the system works really well especially once you understand it and develop a bit of muscle memory for the right clutch and throttle pedal positions to correctly use it.