Category: Electrical Repairs

ABS light on . A quick look at fault codes reveals pump fault . A wiring diagram was used to check power and ground connections . All proved ok .

The pump was removed and a 2nd hand unit sourced as new unit expensive and a repair on existing unit would take too long.

The pump was coded in and test driven to confirm fix.

Into our workshop was this Kia Soul. This is a full electric vehicle and not a hybrid.

The customer wanted a new set of horns fitting. We wired them up completely independent from the existing vehicle wiring so as not to interfere with the sensitive vehicle electronics.

This car came in from another garage who had fitted plugs and coil packs but the fault remained.

The first thing to do was to confirm which cylinder the misfire was on.

With this confirmed we then have to find out whether it’s a fuel, ignition or a fault within the cylinder. The easiest place to start is with the ignition or spark.

A node light is fitted to the plug for the injector to see whether the light pulses with each injector pulse. As this was an intermittent fault at the time of testing it was ok.

We checked fuel pressure and it was also ok. We then put the car back to standard and used our pico scope to monitor the injection pulse whilst the car was running, pico scope is a great way to monitor electrical circuits whilst being non intrusive. The images are all recorded so you can leave the vehicle and if the fault happens whilst your away from the vehicle you can go back and see what happened

Whilst monitoring the injection pulse the signal would dissappear as if being switched off, seen here as a flat line

We then checked the integrity of the wiring from the injector to the ecu just to make sure there were no bad connections or chaffs in the wiring before contacting the customer to tell him that the ecu was at fault. An expensive component which you want to be certain of before swopping. With our experience and training in electrical diagnosis we were confident in telling the customer our results.

This vehicle came in with management light on but running fine.

As well as these codes, fuse 17(engine control unit)  was blowing as soon as the ignition was switched on.

On removal of the engine fusebox burnt wiring could be seen, the main culprit was an earth wirer. The engine loom was stripped out and the burnt wiring replaced. The earth wirer was traced back to the DPF pressure sensor on the exhaust. The sensor was tested and proved ok and once the wiring was replaced the current draw checked and found to be good.

The vehicle was test driven and all was good. On ringing customer with our findings and repairs that were necessary we told them that we couldn’t find a reason for the burnt earth wirer.

The customer then informed us that the problem only happened after trying to start the vehicle and it was dead and the main engine earth was broken. Mystery solved!

Obviously when Trying to start the van and the earth being open circuit it had found its way to earth through the earth wirer on the sensor and with the wirer being alot smaller the amount of current passing down it had melted it.

Ford Fiesta arrived at our workshop as a non runner. The customer said it spluttered a few times then cut out and not run since.  A quick serial scan showed up fuel pressure issues.

We removed the fuel feed pipe from the fuel rail and found no fuel being delivered. Next we removed the back seat to gain access to the wiring to the fuel pump. The wiring was good.

So we then had to get to the fuel pump which is in the tank. The tank has to be removed to gain access

With the tank removed the problem became obvious, the wiring onto the pump had suffered water damage and one of the pins on the pump had rotted off. We manged to remove the rotted pin from the plug and clean the plug up as a new plug isn’t available. 

With a new genuine Ford pump fitted car started and ran great.

Into our workshop was this Citroen van which was towed in as a non runner.

Firstly we plugged in our diagnostic machine and retrieved all the fault codes.

The injector code we thought through experience would be the best to investigate first. The Easiest thing to do first is to disconnect each injector in turn in case one is shorting out dragging down the supply. This proved unsuccessful.

These injectors are Piezo so they are switched on and then the voltage swops round and they are switched off. All wiring was checked from the injectors to the ecu and found to be ok.

We then started  checking the wiring to the ecu because although we could communicate with the ecu there are 3 feeds and 3 grounds that activate different parts of the ecu. It was here that we found 1 of the feeds was missing. This is where accurate wiring diagrams are essential for diagnosis

 

The ecu was accessed and the loom stripped and checked. After much stripping and head scratching the break was found, the tiniest nic in the wirer.

Only if your experts in electrical fault finding could you find a fault like this.

So if your car is suffering from electrical gremlins come see the experts

This vehicle was with us for starting issues, it would crank over fine but not fire.

Unfortunately for this customer they had first been elsewhere with this vehicle and had alot of work done which had not cured the problem.

The garage had unbelievably taken £950 of him without curing the problem and had ran out of ideas of what to do next.

It turned up at our workshop after being of the road for 3 weeks.

Firstly we plugged in our diagnostic machine to scan for any fault codes, there were none relevant to our fault,  so onto live data.

We measured rpm speed and fuel pressure both were low.The starter motor was removed and repaired, the bearings were all worn out due to the excessive cranking.  When refitted the rpm was fine but the fuel pressure still low.

Looking at the previous garages bill one thing they hadn’t done was test the injectors.

A simple spill test which measures the amount of fuel passing through the injectors revealed that one injector was stuck open and so the fuel pressure couldn’t reach the desired level.

A second hand injector was sourced as money now was a real concern for the customer, fitted and coded.

Car started perfectly and ran great. Another customer wishing he’d come to us first!

Renault Trafic non runner.  Been at previous garage for 2 weeks without success.  The immobliser light was flashing normally with ignition off,  when switched on the red light would illuminate permanently without flashing,  signifying a communication error between modules.

In Renaults wisdom to gain access to the UCH the dashboard has to be removed. Once access was gained we can then check continuity between different components. With accurate wiring diagrams a diagnosis can be achieved.

In the engine bay the ECU was exposed and the wiring loom stripped so continuity could be checked, where it was found that the canbus line between the UCH and engine Ecu was open circuit.

Now it was a case of tracing the correct wiring back to the UCH to find the break.

A simple repair was made to the wiring and the van ran fine.

A very happy customer picked up his van within a couple of days and could get back to work.