Autoelectrics tech pages

Breakdown Area Callout

Mobile Motor vehicle repairs
Auto electrical & specialist services
Tel: Shrewsbury 01743 884888

Car, Van or Truck  breakdown ?   Mobile workshop vehicle diagnostic and vehicle repair callout services around Shrewsbury, Telford, Shropshire and Mid Wales areas *subject to availability

Typical causes of vehicle breakdown can include:

Wrong Fuel :

eg Petrol car filled with diesel , Diesel car filled up with petrol.
When a vehicle is refuelled  with the wrong type of fuel at the service station  several problems may result:

1.The contaminated mixed fuel becomes a hazardous waste so needs proper recovery and disposal

2. The engine will possibly either not start or run erratically

3. Further engine damage may occur. The Fuel injection system  fitted to diesel engines can be susceptible to damage caused by accidentally filling with petrol

Fuel injection system breakdown

Possible Cause: Fuel filter blocked, Injectors fault , black smoke, wrong fuel, incorrect system calibration or timing. No crank sensor signal, Fuel pump failure, fuel pump relay, sensor , actuator , or wiring defect, Electronic control unit failure.

Ignition system breakdown

No ignition spark ,Misfire, Difficult starting

Possible Cause: Broken wiring, electronic sensor fault, blown fuse, wiring short, defective components, HT leads, Coil pack, Ignition switch failed, Crank sensor failure, Camshaft sensor failure, wiring.

Lights not working or dim

Possible cause: Blown bulbs, fuses, electrical wiring circuit, switches, control module fault,

If an electrical  fuse keeps blowing on your vehicle - Do not replace with a larger fuse as this may lead to further circuit problems.

Further causes may be failed component, wiring short circuit,

Flat battery

Battery at end of life, low electrolyte level, wiring fault causing current drain, charging system fault, operator error eg lights left switched on.

Alternator fault

Possible cause could be drive belt failure / tensioner failure / battery charge warning light bulb failed or on / dead battery

Clutch Problems

Broken or snapped clutch cable, clutch not clearing, clutch hydraulic fluid leaking, clutch plates worn out or damaged, oil leak onto clutch causing it to slip.

Cambelt or Cam timing

Possible causes include broken belt, teeth missing from belt, idler bearing failure. Failure of cambelt usually results in major engine damage.

Wheels and tyres:

Puncture causing flat tyre , Loss of seal between tyre bead and wheel rim, Leaking valve.

Electric windows

Window stuck open, broken wiring, electric window motor failure, switch fault, control module fault, wiring problem.


keys locked in vehicle. Car keys lost, Key code not matched to immobiliser, key code not read, Central locking not working, Central locking switches , wiring or control module fault.

Suspension fault

Roadspring broken or fractured, radius or control arm bushes, shock absorber broken, shock absorber bushes worn out,shock absorber fluid leaks. Component insecure


Power steering oil leak from reservoir pump or hoses, heavy steering, low tyre pressure, steering rack damage or wear, electric power steering failure, alternator failure, auxiliary drive belt condition. Steering track rod ends.


Detached, fractured or broken pipe, mountings adrift. Broken exhaust manifold studs, Lambda sensor faults, Emissions failure, Catalytic converter or diesel particulate filter blocked, dpf sensor faulty, wiring to dpf sensor faulty,

Engine Oil

Low oil level , engine oil leak, Loss of oil pressure due to wear or oil pump failure. Symptoms : Excessive exhaust emissions, Engine oil warning light on, Low oil pressure registered on guage. Effect : Can lead to seized engine.

Cooling System,

Possible Problem: Overheating :
Possible causes : Low coolant level,  leaking hoses, oil in coolant, oil cooler failure, head gasket failure, thermostat stuck, overheating, coolant temperature sensor or circuit fault, fan motor failure, blocked radiator, water pump failure, drive belt failure. Blocked air conditioning condenser.

Possible Problem: Operating temperature too low , Excess fuel consumption, Difficult starting.

Possible causes : Low coolant level, Thermostat missing or stuck open, Coolant temperature sensor faulty, Wiring fault.

Braking System

Possible Problem: Overheating :
Possible causes : Brake calipers or wheel cylinder sticking master cylinder sticking ,  handbrake cable defective or incorrect adjustment. Disc or drum surfaces scored.
Possible Problem: Efficiency : Pulls to one side under braking, hydraulic system fluid loss, pressure loss.

Possible Problem: ABS fault: damaged wiring, faulty sensor, solenoids, modulator, switches. reluctor, control module


Possible problems: Loss of coded key transponder signal, Immobiliser control unit fault, wiring

Preventative Maintenance Inspection.
While some breakdowns are unforeseeable having a preventative maintenance inspection   done can often identify faults before they occur. For example wiring which may not be secured and chaffing against sharp edges wearing away the insulation ready to cause a short circuit and a breakdown.

Your annual vehicle MoT test is a form of Preventative Maintenance Inspection to identify components corroded, or worn or insecure that may cause a breakdown or threat to other road users. However there are many items not covered by the annual MoT inspection and a pass can mean that a vehicle has only met a minimum standard of roadworthiness. The credit crunch is affecting many people and an attempt is often made to reduce  costs  by extending service intervals.

Vehicle  Breakdown  Assistance

Roadside Breakdown Health & Safety

  • Do not place yourself or others at risk.
  • Where recovery is likely to obstruct flow of traffic inform the police.
  • If possible park straight ahead with your vehicle wheels pointing to a safe impact area (usually the left on uk roads),this is in case another vehicle crashes into the rear of your vehicle whilst it is broken down.
  • If you need to exit from your vehicle do so from the safe side and not into the traffic flow.
  • If your vehicle has been repaired or becomes mobile take care when rejoining moving traffic.
  • Be aware that intermittent faults which may have occurred then apparently disappeared may reoccur without notice.Have your vehicle checked out as soon as possible.
  • Only specialist vehicles and trained technicians should attempt to recover vehicles from motorway networks.

  • Battery test
    This test identifies the ability of the battery to store energy for supplying the high current required to start your vehicle from cold. The electrolyte level of the battery should be checked in accordance with the manufacturers instructions. A battery on a 12 volt system should be recharged when the open circuit voltage drops to below 12.2volts . If a battery is to be recharged off the vehicle it should be done in a well ventilated area away from sources of ignition.

    On a functional charging system the vehicle battery is recharged by the alternator during operation. Warranty on vehicle batteries is usually one, two, three, or four years, and the longer warranty being a slightly higher price. Vehicle batteries are designated specifically to each manufacturers vehicle. It is essential that the vehicle battery is properly secured when fitted.

    Symptoms of a defective battery are no ignition lights coming on , vehicle not starting ,charge warning light staying on with the engine running. Battery faults can also be caused by defects in the vehicle charging system, or by wiring & component faults causing current drain. Battery voltage which is too low or too high due to defective charging system can have knock on effects on vehicle computer controlled systems including engine management and automatic transmission.

    The purpose of the alternator is to provide electrical power for vehicle equipment and to supply energy to recharge the battery as well. An alternator not charging can be caused by defective wiring , loose mountings, loose drivebelt , as well as worn out components within the alternator. The alternator can be tested to a certain extent on the vehicle or removed for bench testing.
    Alternators on some later vehicles have their output controlled by the vehicle onboard computer.

    Starter Motor.
    Defects in starter motor operation can be caused by component failure within the unit or external component failure with items such as battery , wiring, connections, ignition switch, immobiliser. etc

    Timing belt.
    The timing belt synchronises operation of Crankshaft, Valve s and camshafts . Sometimes fuelling equipment also. The cam timing belt is a rubber toothed belt running on sprockets and pulleys. Failure of the cam timing belt usually has disastrous effects for the rest of the engine with pistons colliding with valves. The cam timing belt and idler pulleys should be renewed as part of scheduled vehicle servicing. Engine oil leakage onto the cam timing belt can also encourage early failure.

    Engine cooling system
    Failure of the cooling system can be caused by leaks due to perishing of rubber hoses or failure / corrosion of components, or gasket failure. Signs are engine overheating, coolant leaks, engine not reaching operating temperature, failure of thermostats, fans, etc.
    Loss of engine coolant can result in the engine overheating and a seized engine or cylinder head / engine block damage.

    Engine Oil.
    Engine oil level should be maintained using the correct grade to manufacturers specification. Engine oil & filter change is carried out as part of scheduled servicing.

    Too little engine oil can result in component failure due to lack of lubrication. Too much can cause the running engine to suck up the oil and use it as a fuel and accelerate to destruction. Waste engine oil requires safe handling and disposal.

    Preventative maintenance to manufacturers specification will ensure your vehicle safety , life , and resale value.

    This is just a brief overview and will be added to as I get time. There are many other items requiring regular maintenance such as brakes, axles, gearboxes, lights ,etc.

    Refer to your vehicle manufacturers handbook for further information.

    A few things worth carrying in your vehicle in case of roadside breakdown:
    * Mobile cellular phone *
    * Contact details of a breakdown organisation & relatives *
    * A blanket *
    * Reflective Warning Triangle *
    * High Viz jacket / vest *
    * Flashlight *
    * Tow rope *
    * Battery booster cables *
    * Wheelbrace *
    * Jack *
    * A Road Map so you can specify your location in case of breakdown in unfamiliar areas *
    * Spare engine oil *
    * Spare water *
    * Spare bulb kit *

    We are pleased to help with enquiries relating to vehicle electrical or mechanical maintenance and repair in and around Shrewsbury, Shropshire areas.
    telephone number 01743 884888

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