I'm surprised there haven't been any responces on this... am I asking the impossible ?

 

From what I've seen C1340 is the brake light switch fault code. Can you check the switch is actually actuating and seated properly?

 

First Character - SystemThe first character identifies identifies the system related to the trouble code.

P = Powertrain
B = Body
C = Chassis
U = Undefined
Second Digit - Code TypeThe second digit identifies whether the code is a generic code (same on all OBD-II equpped vehicles), or a manufacturer specific code.

0 = Generic (this is the digit zero -- not the letter "O")
1 = Enhanced (manufacturer specific)
Third Digit - Sub-SystemThe third digit denotes the type of sub-system that pertains to the code

1 = Emission Management (Fuel or Air)
2 = Injector Circuit (Fuel or Air)
3 = Ignition or Misfire
4 = Emission Control
5 = Vehicle Speed & Idle Control
6 = Computer & Output Circuit
7 = Transmission
8 = Transmission
9 = SAE Reserved
0 = SAE Reserved
Fourth and Fifth DigitsThese digits, along with the others, are variable, and relate to a particular problem. For example,a P0171 code means P0171 - System Too Lean (Bank 1). To lookup your particular code, visit our OBD Trouble Codes section.

 

No response from me as I couldn't find that specific code, my searches also pointed to brake switch, but couldn't be certain...

 

Did you manage to clear the C1340 code?
I have it on my Gt now. Same circumstance as you, failed pedal switch, then this.....
MeS pointing to Brake light switch.
I've proved that it's working with a meter though so unsure on the next step.....

 

Hi Alfadisiac

Did you ever figure out the problem? I have the same on my 147 GTA, multiecuscan says brake pedal switch problem.

I have replaced switch and have a new battery, have cleaned main connection on ABS unit with contact cleaner.

My ABS and VDC failure lights come on randomly , after maybe 10 prods of the brake pedal, go away if I switch off the car and restart, then generally come back again later in the drive. sometimes very rarely now they don't come on , only to reappear on next drive.

ABS continues to work even when failure light is on. Of course its a gamble taking for an MOT as to whether they come on or not.

 

Me too. C1340 persists, but new brake switch properly installed etc etc. I don't believe it is the switch at all but perhaps wiring loom or ECU. Luckily I have another 147 I can make comparative measurements against but this is going to be labourious.
Does anyone have a schematic diagram?

 

Due to the way these systems are generally wired, check brake lamp fuse and bulbs. They probably aren't blown but look for evidence of oxidation. Funnily enough I've seen defective 380 bulbs trigger that code when the lights are on so that that as a big clue.

Also, just because one of these bulbs seems to work ok, don't accept that as ok. Use an ohmmeter to measure resistance between base pins ( yes, really- that can trigger the code). Quality bulbs can often prevent this type of fault and much time and expense.

Ensure wiring for centre lamp at tailgate hinge is good. Test in open and shut positions.

Due to all the things it can be, sometimes it may be necessary to have someone follow the car to spot an intermittent lighting anomaly which does not show up under workshop testing.

Crazy to think bulbs and terminals for bulbs/fuses/ multi plugs can do this but they can.
These cars are now old enough to suffer strange faults due to even a single high resistance.

A good anti corrosive spray (ACF-50) for electrical assemblies is a good investment.

 

It is perhaps useful to bear in mind that the ECU for ABS is looking for a voltage signal with a minimum value. AFAIK, there is not an under voltage fault code programmed for the brake light switch.

 

Thanks Fruity, definitely food for thought. I haven't had the change to examine the rear lamps while driving yet but I like your idea. I've had issues with lamps myself but not this symptom.
I've burgled my donor car for a section of the brake light loom and I'm going to make a 'break out' lead so I can have the oscilloscope connected in circuit while using the switch and making direct comparison between cars.

 

I'm confident it's fixed. I replaced the ESP module - not the whole lot, just the circuit board. I'm tempted to carefully cut it open and have a go at fixing it, just for the challenge.