Author Topic: Tyre pressure and auto stop problems solved!  (Read 873 times)

PhilipLB

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Tyre pressure and auto stop problems solved!
« on: March 19, 2023, 08:58:32 PM »
This may not be news to some, but after many months of problems with the tyre pressure monitor on my 2018 Jazz, I have at last found a solution. Well, one of two possibilities actually.

When I had a tyre changed about 6 months ago the tyre pressure monitor started pinging. No matter how much I reset the monitor and checked the tyre pressures, it kept pinging. A Honda dealership recommended fitting two (more) identical tyres (costing about £150), which I did. But it kept pinging. Another Honda dealership then told me there was "nothing" that could be done. However, it occurred to me that the auto-stop had also not been working for the last few months. I had assumed this was due to the cold weather during winter, but now the weather was warming up and it was still not working.

So I then did yet another Google search and found two ways to reset the electronics, as reported by others. One was to pull the bonnet lever while the engine was still running. Then switch off the engine, and open and close the bonnet. The other was to disconnect the battery from the black box next to it. I found that there is a lever-controlled multiway electrical connection on the negative side of the battery, so I disconnected this for a minute or so, and then reconnected it. As it is hard to know whether what you read is really correct, I did both!

To my amazement new messages started to appear on the dashboard, such as "fasten seatbelt" - I had not spotted these before. And the auto-stop now works (and there is a message saying so, which again I had not seen before), and so far (after an hour of motorway driving) I have had no more pinging from the tyre pressure monitor (which I gather uses an indirect method, actually comparing wheel rotation rates.) I can only assume that I had somehow managed to reset the microprocessor and it had updated itself in the process!

I thought others might find this information useful.
« Last Edit: March 19, 2023, 09:05:22 PM by PhilipLB »

ColinB

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Re: Tyre pressure and auto stop problems solved!
« Reply #1 on: March 19, 2023, 10:13:09 PM »
Interesting. I've not had TPMS issues, but the idle-stop thing is annoying. I'd not heard about the bonnet trick, I'll have a try. But I don't recognise what you mean by this:
... there is a lever-controlled multiway electrical connection on the negative side of the battery, ...
I usually just take the negative connector off the battery, but if there's a switch to make that easier that'd be helpful. Any chance of a picture so I can see where this switch is?

PhilipLB

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Re: Tyre pressure and auto stop problems solved!
« Reply #2 on: March 19, 2023, 10:37:13 PM »
The lever is just its way of securing the electrical connector. I'll send a photo tomorrow.
« Last Edit: March 19, 2023, 10:39:13 PM by PhilipLB »

PhilipLB

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Re: Tyre pressure and auto stop problems solved!
« Reply #3 on: March 20, 2023, 09:31:28 AM »
As promised, here's a photo of the battery with two connectors to the right of the negative terminal. The nearer grey lever can be lifted to disconnect the battery from the black box underneath. My guess is that the black box contains the car microprocessor. I have some experience of microprocessors, albeit in a different context, and I know that sometimes they have to be reset by turning off the power completely (not just via a hardware reset signal.) So this may well be what did the trick for me.

I should explain that my local garage had several goes at solving the TPMS problem, and the last time they said they'd reset everything they could think of. It may be that they had unwittingly downloaded some new firmware (which would explain the new messages appearing on the dashboard), but didn't actually disconnect and reconnect the power from the microprocessor to install it properly - just a guess on my part!

Downsizer

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Re: Tyre pressure and auto stop problems solved!
« Reply #4 on: March 20, 2023, 10:02:05 AM »
Disconnecting the power supply briefly is now my first approach to fixing any bit of electronic kit that isn’t behaving!

ColinB

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Re: Tyre pressure and auto stop problems solved!
« Reply #5 on: March 20, 2023, 01:08:37 PM »
As promised, here's a photo of the battery with two connectors to the right of the negative terminal. The nearer grey lever can be lifted to disconnect the battery from the black box underneath. My guess is that the black box contains the car microprocessor. I have some experience of microprocessors, albeit in a different context, and I know that sometimes they have to be reset by turning off the power completely (not just via a hardware reset signal.) So this may well be what did the trick for me.

Thanks, I see what you mean now. I'm a bit nervous about fiddling with clips like that where I'm not sure how to release them, in case I break them. So I just unbolt the negative terminal from the battery post for 5 or 10 minutes, which ought to have the same effect. But so far neither that nor the release-bonnet-whilst-engine-running thing has restored the auto idle-stop. Maybe it'll come back from it's winter holiday in it's own good time, maybe not.

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