Park Brake Fault C1A48-01

[Jetfixeruk]

I have the dreaded park brake fault on my 2012 Discovery 4. The park brake works as normal it engages and disengages with the switch and disengages with application of the accelerator. The fault light will go away after a few starts if the park brake is not used.

The fault manifested itself the day after a day trip sand driving in Fraser Island, back in January, I thought it may be salt water or sand contamination into one of the plugs or into the park brake module itself.
I had the scan tool put on during my service last week, the garage told me the DTC code was C1A48-01, unfortunately I could not afford to pay them to look into it as I am facing a stand down at work due Covid 19. I will have plenty of time to have a look at it myself and do not necessarily need to use the car.

So far I have checked continuity on the CAN bus wires between the park brake module and the plug C0376 on the rear left hand of the chassis rail, these were good. I realise I will have to go further to look for shorts and voltage drop in the circuit. The plugs were dry and seemed well protected with no contamination.

Does anybody have any previous experience with this fault, tips about where to look and what its fix was? Any help appreciated, thanks.
There are no other faults.

[scarry]

Mine misbehaved over a few months,i can't remember the code.

It ended up being the switch,replaced,and been ok since.That was about 3yrs ago.

But its a PITA to replace,unless you have done one before.

Good luck with it.

[Eric SDV6SE]

The fault manifested itself the day after a day trip sand driving in Fraser Island, back in January, I thought it may be salt water or sand contamination into one of the plugs or into the park brake module itself.

Have you taken the wheel off, removed the plug and stuck a hose inside the drum? Probably full of sand, stopping the mechanism from actuating properly.

[matti4556]

I'm with Eric. Do the easy /cheap things first. Clean and readjust park brake shoes. This happens a lot to me after a day on the beach or dirty water crossings.

[Jetfixeruk]

Mine misbehaved over a few months,i can't remember the code.

It ended up being the switch,replaced,and been ok since.That was about 3yrs ago.

But its a PITA to replace,unless you have done one before.

Good luck with it.

Do you mean the park brake switch?

I have had it out to check the wiring, its easy to get out. If you need to get it out again or if anybody needs to get one out:

Remove the cup holder and the drip tray underneath. Unplug the the connector from the back of the park brake switch.

Prise out the rubber cup in front of the park brake switch with a trim tool or teaspoon, undo the torx fastener, and slide the switch forwards up and out.

I pulled the 30 amp Park Brake fuse before I did it.

I did read some one suggesting to remove the centre console and removing it from the back, this isn't necessary.

[Jetfixeruk]

Have you taken the wheel off, removed the plug and stuck a hose inside the drum? Probably full of sand, stopping the mechanism from actuating properly.

Thanks I'll try it.

The Land Rover manual threw me to more complex troubleshooting with the below which concentrates on wiring:

C1A48-01Warning Lamp - General electrical failure

Possible Causes


Parking brake actuator
module to instrument
cluster warning lamp
circuit open circuit


Parking brake actuator
module to instrument
cluster warning lamp
circuit short circuit to
ground


Parking brake actuator
module to instrument
cluster warning lamp
circuit short circuit to
power


Parking brake actuator
module fault
Instrument cluster
fault

Action


Check the parking brake actuator module to instrument
cluster warning lamp circuit. Refer to the electrical circuit
diagrams. Rectify as necessary. Refer to the warranty
policy and procedures manual if a module is suspect. Clear
DTCs, complete drive cycle 1 to test for normal operation

In the description and operation it says that low voltage in to the actuator can also bring on the warning light.

[PerthDisco]

As above - clean it out and adjust it. Works 99% of time.

When was it last ‘serviced’?

[Jetfixeruk]

As above - clean it out and adjust it. Works 99% of time.

When was it last ‘serviced’?

Definitely going to try the clean and adjust thanks.


Car last serviced on 1st April. I asked them for the code then. I had a few preventative maintenance jobs done (trans flush and coolant crossover pipe) so the bill was big enough as it was, thought I'd tackle the brake fault myself.

[Jetfixeruk]

I have cleaned out and adjusted the park brake drums.

Checked for short circuit in the park brake CAN bus and loom up to the rear LH wheel arch connector C0376. Checked CAN bus continuity up to the centre console.

Fault persists.

It still will go away after a few runs without using the park brake

[Jetfixeruk]

After much head scratching and trawling through forums I finally came up with a fix for my Park Brake Fault and associated DTC C1A48-01.

It was a broken wire between connector C0376 and the BCM, the LR manual is misleading about this.

For those of you that want more detail and as to how it took so long to find, read on and refer to the wiring manual pages if you can:

For DTC C1A48-01 the D4 workshop manual suggests the below troubleshooting actions which in my opinion are misleading:

Check the parking brake actuator module to instrument
cluster warning lamp circuit. Refer to the electrical circuit
diagrams. Rectify as necessary. Refer to the warranty
policy and procedures manual if a module is suspect. Clear
DTCs, complete drive cycle 1 to test for normal operation

Referring to the D4 wiring diagrams 265-05 and 418-00 the only circuit that goes from the park brake actuator to the instrument cluster is the high speed CANBUS. I checked for continuity and shorts on high speed CANBUS at various points on the car and everything checked out OK. I also checked all of the wires in the short run from the EPB to the connector C0376 on the chassis rail, again no faults.

If the wiring is good Land Rover suggests that the park brake module or the instrument cluster may be faulty $$$$$!!. I almost pulled the trigger on spending $2K to have the EPB module replaced. I discussed the issue with a mechanic at my local LR specialist who said that this fault looks like a wiring problem, and I should look further into it before changing the EPB. So subsequently I checked the splices in the CANBUS loom in the LH rear of the vehicle and almost considered cutting the CANBUS at the EPB to see if it created any other faults, as the EPB is the last module on the CANBUS. Again I could not find any faults.

So it was back to the trawling the internet, researching the Kuester (EPB vendor) website and BMW wiring diagrams. BMW use what looks like to be exactly the same park brake actuator, I found nothing of value here. During this time I chanced upon a D3 EPB wiring diagram.

The D3 EPB wiring diagram 206, shows that in addition to the HS CANBUS there is a “signal lamp” circuit that goes directly from the EPB to the instrument cluster.
Cross referring this diagram to the D4 diagram this signal lamp (now called status lamp) wire goes from the EPB to the BCM, on the D4 the status lamp (P) is then triggered from the BCM over MS CANBUS to the instrument cluster.

My presumption for the D4:

Is that this signal lamp circuit gives a discrete signal to the BCM that illuminates or extinguishes the RED park brake applied symbol via MS CANBUS to the instrument cluster. In the D4 if this disagrees with the HS CANBUS signals it brings up PARK BRAKE FAULT message and DTC C1A48-01. This is only my presumption based on what I know about aircraft systems and I have no technical data to back this up.

Back under the car to check this circuit from connector C0376 (L/H rear wheel arch on top of the chassis) forward towards the CJB.

Adjacent to the back of the connector there was a discoloration to the GREEN wire in question, I probed the wire pushing a pin through the insulation (not recommended unless you plan to seal it back up again) and voila there was no continuity from the pin in the plug to where I pushed in the pin about an inch back from the connector.

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To repair the connector, I pulled out the grommet behind the wheel arch out and pulled the connector and loom into the rear load bay after removing the LH rear sidewall. I removed the pin from the connector and soldered on a new piece of wire, I cut back the old wire and spliced the new piece into the loom with a solder splice.

162189162190

If you download the connector diagram from Topix it states on diagram that the “connector housing is not serviceable”. This is absolute rubbish, information on how to dismantle and repair the connector is available from the manufacturer TE along with part numbers of pins and sockets. https://www.te.com/usa-en/product-1438842-1.html. Plug and socket can be pried apart and pins removed with basic tools, pliers and small screwdrivers.

I believe that some of the D4 workshop manual text has not been amended to reflect the change from Discovery 3 systems to Discovery 4 and the troubleshooting for C1A48-01 still refers to Discovery 3 wiring. The D4 vehicle workshop manual troubleshooting instructions should be amended to read:

Check the parking brake actuator module to body control module
status lamp circuit. Refer to the electrical circuit
diagrams. Rectify as necessary. Refer to the warranty
policy and procedures manual if a module is suspect. Clear
DTCs, complete drive cycle 1 to test for normal operation

The information from TE.com about dismantling the connector was invaluable, scroll down to the instruction sheets on the webpage. The repair parts cost me $7.

THanks for reading, I hope this helps somebody else.

Michael.

[Eric SDV6SE]

Awesome Michael, I love a good troubleshoot and fix.

[DiscoJeffster]

You’re a legend mate. Thank you for investing the time to clearly document this. This is community.

[Jetfixeruk]

Thanks Eric,

If the manual had the correct text I would have found it on the first look. On the plus side I learnt an awful lot about the car.

[Plane Fixer]

Like trying to fix Metro wiring!!!

[DiscoDB]

Thanks for sharing Michael. I suspect as the D3/D4 ages we will all have to get better at diagnosing bad wiring issues.

[Toni Santos]

Después de mucho rascarse la cabeza y buscar en los foros, finalmente se me ocurrió una solución para mi falla de freno de estacionamiento y el DTC C1A48-01 asociado.

Fue un cable roto entre el conector C0376 y el BCM, el manual de LR es engañoso sobre esto.

Para aquellos de ustedes que quieran más detalles y cómo se tardó tanto en encontrarlo, sigan leyendo y consulten las páginas del manual de cableado si pueden:

Para DTC C1A48-01, el manual de taller D4 sugiere las siguientes acciones de solución de problemas que, en mi opinión, son engañosas:

Verifique el módulo del actuador del freno de estacionamiento en el circuito de la lámpara de advertencia del grupo de instrumentos
. Consulte los diagramas de circuitos
eléctricos. Rectificar según sea necesario. Consulte la política de garantía
y el manual de procedimientos si un módulo es sospechoso. Borrar
DTC, ciclo de conducción completo 1 para comprobar el funcionamiento

normal Consultando los diagramas de cableado D4 265-05 y 418-00, el único circuito que va desde el actuador del freno de estacionamiento hasta el cuadro de instrumentos es el CANBUS de alta velocidad. Comprobé la continuidad y los cortocircuitos en el CANBUS de alta velocidad en varios puntos del coche y todo salió bien. También comprobé todos los cables a corto plazo desde el EPB hasta el conector C0376 en el raíl del chasis, de nuevo sin fallos.

Si el cableado es bueno, Land Rover sugiere que el módulo del freno de estacionamiento o el grupo de instrumentos pueden estar defectuosos $$$$$!!. Casi apreté el gatillo al gastar $ 2K para reemplazar el módulo EPB. Discutí el problema con un mecánico de mi especialista local en LR, quien dijo que esta falla parece un problema de cableado y que debería investigarlo más a fondo antes de cambiar el EPB. Así que posteriormente revisé los empalmes en el telar CANBUS en la parte trasera izquierda del vehículo y casi consideré cortar el CANBUS en el EPB para ver si creaba algún otro fallo, ya que el EPB es el último módulo del CANBUS. Una vez más, no pude encontrar ningún fallo.

Así que volvimos a buscar en Internet, investigando el sitio web de Kuester (proveedor de EPB) y los diagramas de cableado de BMW. BMW usa lo que parece ser exactamente el mismo actuador de freno de estacionamiento, no encontré nada de valor aquí. Durante este tiempo, me encontré por casualidad con un diagrama de cableado D3 EPB.

El diagrama de cableado D3 EPB 206 muestra que, además del HS CANBUS, hay un circuito de "lámpara de señalización" que va directamente desde el EPB hasta el grupo de instrumentos.
Refiriendo este diagrama al diagrama D4, este cable de la lámpara de señal (ahora llamada lámpara de estado) va de la EPB al BCM, en el D4 la lámpara de estado (P) se activa desde el BCM a través de MS CANBUS al grupo de instrumentos.

Mi presunción para el D4:

Es que este circuito de lámpara de señal da una señal discreta al BCM que ilumina o apaga el símbolo de freno de estacionamiento ROJO aplicado a través de MS CANBUS al grupo de instrumentos. En el D4, si no está de acuerdo con las señales HS CANBUS, aparece el mensaje PARK BRAKE FAULT y el DTC C1A48-01. Esta es solo mi presunción basada en lo que sé sobre los sistemas de aeronaves y no tengo datos técnicos que lo respalden.

De vuelta debajo del coche para comprobar este circuito desde el conector C0376 (paso de rueda trasero L/H en la parte superior del chasis) hacia adelante hacia el CJB.

Adyacente a la parte posterior del conector había una decoloración en el cable VERDE en cuestión, sondeé el cable empujando un alfiler a través del aislamiento (no recomendado a menos que planee volver a sellarlo) y listo, no había continuidad desde el pin en el enchufe hasta donde empujé el pin aproximadamente una pulgada hacia atrás del conector.

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Para reparar el conector, saqué el ojal detrás del paso de rueda y tiré del conector y el telar en el compartimiento de carga trasero después de quitar la pared lateral trasera izquierda. Quité el pin del conector y soldé un nuevo trozo de cable, corté el cable viejo y empalmé la nueva pieza en el telar con un empalme de soldadura.

162189162190

Si descarga el diagrama del conector de Topix, indica en el diagrama que "la carcasa del conector no se puede reparar". Esto es una absoluta basura, la información sobre cómo desmontar y reparar el conector está disponible en el fabricante TE junto con los números de pieza de los pines y enchufes. https://www.te.com/usa-en/product-1438842-1.html. El enchufe y el zócalo se pueden separar y quitar los pasadores con herramientas básicas, alicates y destornilladores pequeños.

Creo que parte del texto del manual de taller D4 no se ha modificado para reflejar el cambio de los sistemas Discovery 3 a Discovery 4 y la solución de problemas para C1A48-01 todavía se refiere al cableado Discovery 3. Las instrucciones de solución de problemas del manual de taller del vehículo D4 deben modificarse para que digan:

Verifique el módulo del actuador del freno de estacionamiento al circuito de la lámpara de estado del módulo
de control de la carrocería. Consulte los diagramas de circuitos
eléctricos. Rectificar según sea necesario. Consulte la política de garantía
y el manual de procedimientos si un módulo es sospechoso. Borrar
DTC, ciclo de accionamiento completo 1 para probar el funcionamiento

normal La información de TE.com sobre el desmontaje del conector fue invaluable, desplácese hacia abajo hasta las hojas de instrucciones en la página web. Las piezas de reparación me costaron 7 dólares.

Gracias por la lectura, espero que esto ayude a alguien más.

Miguel. .

Hello Fossicker, good afternoon, I have the same fault code C1A48-01. I have already checked the actuator connectors, those in the rear left wheel arches, one black and one gray and front right, and all the cables are in good condition. I have also looked at the fuses and the handbrake works both to put on and take off. The black connector that you mentioned is the one that is removed when you remove the body or is it another one that I have not controlled. Could you give me some advice on what else I can look at? Thank you.