Rewire my Fiat 500

My brand new eleven years old Fiat 500 developed a problem (in fact it came with it) by which at some point while you were driving the seat belt buzzer and light would come up scaring the s..t out of me. I now live in the Netherlands and despite the weather I was used to in the UK isn’t too different here I’m still not quite used to the Vikings’ climate (love the TV series though).

I knew I had to sort this sooner than later but it’s the middle of winter and I don’t have a garage!

Put the wires back together

In moving the passenger seat back and forward the cable bundle underneath came off and got trapped in the rail possibly. In any case it got chewed up pretty badly severing some cable and damaging pretty bad others. The sleeving was also damaged and needed to be redone.

As the damage was very close to the main sleeve I had to first cut through is in order to expose the internal wires.

I then cut the wires and stripped them. I placed a piece of heatshrink tubing for each of the wires I cut. I then soldered each end together.

The joints are then well protected by the tubing which I heated with a lighter. Make sure not to burn the tubing by keeping the flame of it. It needs to heat up not burn. A heat gun would have been better also because it was bloody cold out on the road but the lighter was all I had 🙂

In the end I used rubber tabe which protects the wires, provides good insulation and make the whole thing look pretty neat.

Verify that everything works OK

I performed the diagnostics with Multiecuscan and a kit I bought on eBay from iDiagnostics. The kit I have is an ELM 327 OBD2 USB interface there are many available on the market but not all are good so be careful with what you buy. Check this post on the forum for more information.

Checking things with Multiecuscan

I had already scanned the CAN bus in search of ECU by using the F11. You get a report similar to this which will tell you what ECU could be seen. Be wary though to find the right ECU you need to use the right adaptor even when performing the scan, maybe obvious but it got me a few times.

Here is a nice table I made.

With this bits of preparation done I then moved to verifying that the seat belt and the airbag weren’t complaining anymore. I used a laptop from a friend which has a paid for licence (€50). Some of the snapshots of the interface are in Italian (bloody foreigners 🙂 but they should be fairly self explanatory.

Using the Yellow cable I found the ECU I was after. I connected to it by selecting it in the Control Module section and pressing F10.

The program will remind you to use the right cable!

The dashboard cleared the alarm for the faulty Airbag on the passenger site (sorry haven’t got picture of it before and after). I had a look at the Airbag parameters and they seemed to be in order all reporting the same resistance.

I then looked at the seat belts with

and without the seat belt connected in the passenger seats. Note that when the seat beat is not plugged in the circuit is open and no current flows.

It might not be the most thorough analysis but using this diagnostic tool made me more confident that the repair was good.

A final word on OBD2, CAN bus and Multiecuscan

The OBD2 interface is your way in into the CAN bus of your car which allows you to connect to the various ECU (Electronic Control Units) that deal with the subsytems in your car e.g. Airbag, Engine, Doors, Audio system, etc. There is a for Dummies article which explains more if you are curious about OBD2, CAN bus, etc.

!!Be careful when using this equipment as you could render your car unsafe to drive so use this information in this article at your own risk!!

Each car nowadays has an OBD2 interface and it’s generally somewhere near the driver seat, if you don’t know where to find it you need to either read the user manual or search on the internet about it as it might be tricky to find. Mine was just on the left of the steering wheel next to the door (I’m in the continent so I drive on the right side of the road) hidden behind a plastic lid.

The kit I bought comes with several coloured adaptors. You will need to consult this page to understand which adaptors are required for each specific car. Note that multiecuscan can be used only for some brands if your car isn’t amongst the vehicles in the list then you will need a different program and possibly an another type of interface for your OBD2 port. To find the right vehicle in the very long page you are presented with I couldn’t find any other way but CTRL+F and search with the browser within the page content.

Lastly if you are entirely new to Multiecuscan I strongly suggest you head first to read the manual, really, you need to know what to do to install it, if you follow the instructions it’s super simple. Also make sure to check their forums which are full of useful information.

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