[vigsom]

Introduction

Sometimes, cars throw up never heard of issues, and most likely than not, a systematic problem solving process would eventually lead to a solution. This is a quick account of how such a problem was solved, although the process followed was not necessarily systematic.

"Curriculum" Vitae

The car: A 2011 Hyundai i10 Sportz AT, done just 42,000km and in absolutely top shape

The driver : A lady surgeon for whom this car has to offer a reliable home to hospital(s) commute, since most of her professional life revolves around emergencies

The problem

The car was doing its duty dutifully all along, but a few days ago, the AC blower would stop intermittently, and gradually remain off for the most part and eventually stopped altogether. Feedback received was:

1. Blower was not turning on at any of the 4 speed settings
2. AC compressor switch when pressed wasn't turning on

It was as if there was no power to the AC module. Typical issue one would notice in the aircon was the compressor clutch failing to engage, and that would most likely be due to a weak compressor clutch electromagnet, but this one was strange. I had some time on hand off work, so decided to get down to see if I could solve this.

[vigsom]

Initial solutioning

The common formula of checking for blown fuses, and power supply to the circuit

Constraints faced

1. Owner manual not available; so getting to know the relays in the BCM was a task
2. Failing light - the car was to come at 3pm but eventually came at 6pm
3. Inside fuse cover did not say anything about the relays; it only talked about the fuses
4. (Expecting too much from an owner) - service manual n/a

The process of finding out the culprit

1. First checked the Aircon Switch fuse, the Aircon Compressor fuse, Aircon Compressor relay, Aircon blower relay, the Aircon Blower fuse. The fuses were all fine (checked for continuity using a multimeter), the relays looked fine too and showed NO signs of wearing. In fact, the relay internals were fine too
2. On the inside of the car, checked for any fuses related to the Aircon switch and found none
3. Noticed that one brown relay (35A) on the inside was rather hot compared to all other relays in both the fuse boxes. Since this was an unknown relay, and led me to suspect it due to its high temperature, I put the "apparently good" 35A relay of the AC blower in its place but the Aircon still did not turn on.
4. Another relay was swapped and put into the Aircon blower relay slot but still did not work
4. This was like hitting a dead end, but I do not generally give up. For trial, I swapped the Aircon blower relay with yet another 20A relay, and bingo, the aircon started working. The good looking 35A relay, which showed no signs of wear or sparking, or pitted points inside had actually failed.

Happy that the problem was solved, I asked for another relay from a store closeby and decided to put this new relay into the slot for the Aircon blower, while shifting the OE relay back to its original slot for the Radiator Fan. All's well that ends well, or that's what I thought. I packed up my few tools and was ready to leave when I discovered that the power windows were now not working. Oh God!

Back to diagnosis

With no manual in hand, I was shooting in the dark (it was 7:30pm and dark already). I chanced on a video that actually showed all the fuses and relays on the i10. Only then I realised that the brown relay on the inside was the Power Window relay. Then it dawned on me - the "hot" relay might actually have been the good one while the normal temperature 35A one removed from the Aircon blower slot and slotted into the Power window was indeed the culprit - and sure enough, as soon as the "hot" relay was put in, the windows started working.

Again, time to rejoice, but not yet!!

The fuses inside the car


Relays unknown initially - the light brown relay below the green one is the one for the power windows


Relays and fuses in the engine bay fuse box - the ones marked green were checked


Fuse box in the engine bay


New blue relay in place of the defective one - this one action made all of the aircon controls and equipment work


Original Denso relay - 130 bucks


vs a Denso look alike - 60 bucks


O/E/N relay vs Hyundai OE

[vigsom]

A new problem surfaces

Aircon solved, Power window issue (created and solved), and now the brake lights weren't coming on. Sometimes, when we see multiple electrical issues, the normal tendency is to suspect the wiring, without realising that these cars' wiring is generally well engineered and built to last long. I was clueless on what to look for now but the brake light fuse was in order (continuity checked using a multimeter). On looking deep inside though, I found the brake switch coupler decoupled. Who did this? I dunno.

I burrowed myself into the driver footwell, coupled the coupler and found the brake lights always on; the plunger on the brake switch was moving in and out, but the lights were on always. What does one suspect? A faulty switch, and a common issue in the smaller Hyundais (I've seen folks owning i10s, new Santros having dead batteries due to these lights being on for long)

Switch ek khoj (Search for a switch)

The next day, while scouting for this switch, the ASC refused OTC sales, and the exact same switch was not available anywhere. There was one from Anupam Industries and one from Uno Minda available on line but delivery was a cool 10 days.

Examining the brake lever and the switch closely by getting deep into the footwell

1. I had some free time two days after the Aircon saga, and decided to check what was on.
2. Found that there was this button sized bush (some cheap polymer) that resembled the washer used in household taps. That had cracked and I could see pieces on the floor mat.
3. I also noticed that adjusting the brake switch did make it work but after a few strokes of the pedal, the lights remained on always.
4. It was then that I noticed that there was this small hole in the portion of the brake pedal lever that contacts the switch plunger, and then realised that the broken bush must have been there

Solution development

I came out of the burrow, and thought of three options

1. A washer stuck to the contact part of the brake pedal using double sided tape
2. A piece of plastic stuck to the contact part using double sided tape
3. Inserting either of the two parts of a fender flap or grill press button (the one that comes in two parts)
4. Speaker mounting clip inserted into the contact part

I scored off options 1 and 2 as the washer could slip out in a few months when the double sided tape adhesive would lose its properties. Then tried option 3 but the clip could not cover enough area, plus it would also slip off over time. Finally tried the press button, and it fitted perfectly in place. It looks like by design, the brake switch plunger (non-metallic) is designed to only have contact with another non-metallic part.

Pieces of the broken bush


Three possible solutions - speaker clip, washer and fender flap press button


On the job testing each option


Speaker clip inserted in the contact part of the brake lever - not the best solution as it wasnt covering enough area plus it could slip off


Fender flap button in position and there to stay (hopefully!)


Brake switch in position and working finally


What could I have done better?

On the Aircon diagnosis, I could have

1. done the job faster had I armed myself with information on those unknown relays on the inside of the car
2. understood how to test for faulty relays without relying on visual inspection alone

On the brake switch issue

1. I think I worked like a stud

Key Learnings

1. There is always a solution to an automotive issue, and it is best diagnosed oneself, patiently and systematically
2. Perseverance (the Never Give Up spirit) pays in the end
3. A good quality automotive relay has a removable cover; lesser priced ones are "sealed"
4. Satisfaction derived by solving issues oneself is invaluable
5. Smile on the face of the delighted owner is worth a million bucks!!

[Aditya]

Thread moved out from the Assembly Line. Thanks for sharing!

[Trueno]

Hey @vigsom,
We used to own an i10(facelift) as well so if you want, I can send you the scanned copy of the owners manual.

[lemedico]

(Relay)Transplant surgery on a surgeon's car!
Good going on those mends, and shame on the OEMs who do not sell components over the counter.