ABS sensor failure

So it seems these things happen in threes! The ABS sensor light came on the dash for the second time in my ownership. This means parts of the ABS system is not working and so the system is deactivated. Typically it is an ABS sensor on one of the wheel hubs that has failed and needs replacing. While the light is on, the ABS system will not be functioning, so be aware that you are likely to lock up the wheels under heavy braking especially in wet conditions.

Replacing an ABS sensor is quite a straightforward job and can save you money on garage bills if you choose to do it yourself. All you need are some basic tools, and ideally a sturdy vice clamped to a bench or similar.

To diagnose which ABS sensor is at fault and how to replace it, I’ve written a guide here to talk you through the process.

MOT passed!

I put the 106 in for another MOT at a council MOT test centre conveniently located next to the office. Unfortunately it failed again. This time it failed on:

  • Rear brake efficiency
  • Ball joints too much play
  • Emissions over on CO.

The play in the ball joints was only evident on an MOT rig that shook the car, the tester said a crowbar wasn’t enough to budge them. I asked if he could test it with a crowbar then!
The emissions  issue was solved by swapping the Cat over which I had luckily bought months ago as a spare in the garage.
The rear brakes were doing about 25% of the effort they should have been, this turned out to be the rear brake compensator. This device alters how hard the rear brakes work  depending on the load of the car. E.g. if you fully load the boot with 70kg of kit, the compensator will ensure the rear brakes work harder. Unfortunately these often seize and regularly fail the MOT on older cars.

I decided to take it into the garage since the rear brake efficiency was definitely going to be the rear brake compensator not working as designed, and as it is tucked up behind the rear beam, it’s not a easy job when you don’t have a hydraulic ramp. Also, if the compensator needs removing and you round off one of the brake pipes, its a real pain to sort out.
I can recommend JP Auto Technics, in Swallownest as a fast, efficient garage. Theses boys have seen all sorts of motors from everyday cars to fire breathing high spec Rally cars. They sorted out the jobs in no time and got it MOT’d with no hassle.

Rear brake bleed and service

One of the MOT failures was “Nearside brake application uneven.” This suggested to me that the brakes needed thoroughly bleeding to remove any air, and the caliper checking to make sure it was moving correctly and applying brake pressure to the disc. Bleeding the brakes is easier if you have a friend to hand. You’ll need an 8mm brake spanner for the bleed nipple. Now these can be very fragile and often snap inside the caliper. Even though they often snap in the closed position it still means you now can’t bleed the brakes. Some people recommend soaking the nipple in WD40 overnight, or ‘shocking’ the nipple loose using a deep socket. Assuming you can free the bleed nipples on all calipers, you should start bleeding at the caliper furthest away from the Master cylinder, then proceed in order, ie. N/S/R, O/S/R, N/S/F, O/S/F. To bleed a caliper, attach a brake bleed kit to the nipple, loosen the nipple and ask an assistant to depress the brake pedal. At the bottom of the pedal’s travel, ask them to hold it there and close the nipple. Release the pedal and reopen the nipple. Repeat this process until only fluid comes out of the bleed nipple and no air bubbles are present. IMPORTANT: Make sure you keep the brake fluid reservoir topped up with fluid. If it drops too low, you’ll draw more air into the system, defeating the purpose of the exercise and you’ll have more work on your hands. You may need to go round all 4 calipers two or more times to remove all the air, depending on how much is present.

With this done, I removed the brake disc and carrier so I could check the movement of the piston. It was very stiff, so I greased the piston lightly and wound it back in. I got an assistant to press the brake so the piston was pushed out and wound it back in again. I did this 3 or 4 times and the piston loosened off nicely so it was moving more freely. To help pass the MOT, I added to new brake pads while I was there. A very easy job – simply remove the clips from the old pads and tap out the slider with a screwdriver. Grease up the slider and replace it together with the new pads. Press the clips back onto the pads and ensure the slider has its retaining pin fitted. Replace the disc and pad carrier and voila.

ABS sensor failure

ABS lightSince the ABS light was on the dash (an MOT failure) I set about trying to solve the issue. First up was the issue of trying to figure out which sensor was at fault. Usually a garage will use the diagnostic machine to find out which sensor is providing faulty or no reading. Obviously I don’t have the diagnostic machine on hand, but there is another (cheaper) way…
I signed up on to become a full forum member for £5. This allows you to view the diy guides, one of which is diagnosing an ABS sensor failure. For full members the article is here. Using the guide I determined that the N/S/R sensor was at fault.

I logged onto the Eurocarparts website and ordered the correct ABS sensor for the car. Lo and behold it arrived, and turned out to be the wrong ABS sensor. So I sent it back and browsed ebay for the correct sensor. Having ordered the sensor, a nice Glaswegian guy called to check my registration and make sure it was the correct one. The sensor arrived and was thankfully the right one.

To change the sensor first get under the rear of the car and trace the ABS sensor back under the rear beam to the blue plastic plug. Remove this and work your way back to the hub, removing the
cable clips as you go. To get the old ABS sensor out requires patience and brute force!
Remove the rear disc protector by removing the 3 torx screws in the back of the hub. Next its helpful if you remove the brake pad carrier and brake disc. This allows you full access to the ABS Sensor. A set of Mole grips are very useful for grabbing the sensor and removing it. If it’s never been changed, you’ll need patience as it will almost certainly be near-seized in the hub. You will destroy the sensor on removing it, I managed to pull the electronics out of it metal casing! To removed the casing from the hub I had to hammer it with a screwdriver until finally, it came out. Clean the hole in the hub and gently work the ABS sensor in until it is in place. Once the ABS sensor is connected up, it will take time for the ABS ECU to recognise the sensor is now working and turn off the ABS sensor light on the dash, so take the car for a run for a few miles and job done.

Brake light fix

Brake light issuesThe 106 has had a rear brake light out for a while now. I’d checked the rear bulbs, circuit board and wiring were all ok so I took a chance on and bought a brake pedal switch from Peugeot in the hope that it was the switch at fault.

The part number for the switch is 4534.52

Now although it’s awkward to position yourself to see/feel the brake switch, it is very easy to change. I managed to spend about 3 minutes looking for the switch and 2 minutes changing it over!

Youll need to open the drivers door and lean down head first into the footwell. Position yourself to look up to the top of the brake pedal. You might have to pull a little bit of carpet out of the way. Push the brake pedal down with your hand and you will see the switch at the top of the pedal’s travel. To remove the old switch, unclip the loom from the top of it. Now grab the top of the switch and wiggle it back and forward until the ribbing on the bottom half of the switch slides out and you can withdraw it.

Push in the new switch, reconnect the loom and test your brake lights. Hopefully you’ll just have solved the problem for a few pounds and 5 minutes of your time!

Brake upgrade

The brakes took a bit of a beating at the but were quite poor even before that. So I started looking at brake upgrades to see what was feasible. Since I wanted to retain the standard 14″ wheels, the largest caliper I could fit was the 266mm setup from the 306 Xsi, 206 GTi, Berlingo and a few other models. Now there are several combinations of caliper, pad, and disc and some require modifications. The best resource I could find after hours of reading was this comprehensive thread. It lays out alll the combinations available to you, and what works well.

So I found a set of calipers on ebay, and I sent them off to be refurbished with fresh seals and painted in silver. These came back painted up and so I needed to set about locating the rest of the rebuild parts, pads and discs.

I found that the spring clips needed to retain the brake pads from Peugeot were only sold with a set of pads. So I ordered these in with a view to selling the pads on. I also needed two fitting kits consisting of two sliders, rubber boots, bolts and 13mm bolts. Finally I ordered 4 206 gti torx bolts from Peugeot to fit the yokes.

Pad-wise, I decided on Ferrodo DS2500 pads (part no FCP1399H) which I’d used before on the 306 and are an excellent compromise for road and track. These were quite pricey at £110 from Demon Tweeks/Camskill but you realise they really are worth it when you try them.

The upgrade started badly, with me snapping a rear caliper bleed nipple leaving me searching for new new calipers. This was despite soaking the bleed nipples for 2 weeks in WD40, and being extra careful to remove them. They’re just rubbish! So I spend a good hour swapping over a new rear caliper. Now the rear was bleedable I set about test fitting the new front brakes.

Trial fitting showed the yokes of the new calipers fouled on the hub, which wasnt unexpected, but this meant you couldn’t fit both hub bolts and I had to break out the angle grinder. (Check out my protective Aviators!!) To correct the problem, I ground down some of the yoke until it fitted, painted and relaquered the ground area. I fitted the new brake discs and yokes, then broke out the new Ferodo DS2500 race pads and fitted them to the yokes with a bit of copper grease in the appropriate place. With the pads fitted, I built up the caliper using new sliders and bolted the calipers on. I then bled the brakes, removing a lot of air, and the brake pedal firmed up nicely. I was wondering whether I needed to use a GTi-6 or 406 master cylinder, but the pedal currently feels so good that I may not bother.

The bedding in procedure varies depending on who you talk to. Ferrodo recommend 25-30 stops at 50% of pedal pressure for 4-5 seconds. So I took the car for a spirited drive down my favourite local country roads. With the bedding in completed and the lovely whiff of brakes inside the cabin, I let them cool off and tried using them in earnest. The pedal has a little dead travel at the top but the stopping power is infintely much better than the OE setup. The progressive stopping power really inspires confidence, it really is worth all the effort and expense to carry out this upgrade and I recommend it to any GTi owners still on the OE calipers. It has transformed the performance, offering you the ability to press on and pull up smartly. I hope to write back on how they perform at Angelsey next week.

Next trackday booked!

Today I booked the second trackday of the year, this time I’m off to Wales to drive the Angelsey coastal circuit on the 20th May. I visited Anglesey last year, as I was on holiday in the area, and the backdrop to the track really is stunning offering fantastic sea views. The day is being run by the excellent Circuit days in open pit lane format, at a reasonable price of £149 including free driver tuition. 

Now the race is on to complete modifications to the car ready in time. The main area that needs addressing is the front brakes. I would like to fit some 266mm brakes from the 306 XSi models on the front to offer a little more braking power. An upgrade from the standard 247mm setup, these calipers are well known to offer good performance, fit under the standard 14″ alloys,  as well as being cheap as chips to buy. 

With places still available why not come along and experience driving your car to the limit in a safe environment amongst other enthusiasts?

Rear Brake renewal

For weeks I’ve noticed the rear brakes sticking on, particularly at the beginning of a journey. I finally got round to ordering some brake discs from BuyPartsBy for the princely sum of £21 delivered. Since I already had  a spare set of rear brake pads from the 306 which shares the same rear caliper, it was time to get started and sort out the rear brakes.

With the sun shining it wasn’t too much of a chore. I timed it right as the pads on the nearside were almost down to their backing plate and were clearly not contacting the disc 100% of the way across.

I removed the pad carrier, cleaned it out, replaced the pads and greased the sliders. I then wound back the caliper pistons which were extremely stiff, but loosed up eventually with a little persuasion and copper grease. I noticed the dust boots need renewing at some point in the future but I’ll leave that for now. A bit of threadlock on the bolts and the car was dropped back down on it’s wheels.

I took the car for a drive and the difference was notable, no drag from the brakes, and the car felt livelier and more responsive – clearly it was being held back quite significantly before. Hopefully eliminating the binding brakes may well help to improve the fuel economy as well (see mpg post )