LF Auto Electrics

2022 Ford Transit — No HVAC operation, CAN network fault diagnosed properly. ⚡

This Transit came in with the HVAC completely inoperative. The customer had previously been advised that the BCM was at fault, which would have meant a considerably more expensive repair.

Rather than condemn a module based on symptoms alone, we started with proper circuit testing.

Powers and grounds were checked and confirmed, followed by CAN network testing. That immediately highlighted the real issue — we had approximately 12V present on the CANBus, which should not have been there.

From that point, the wiring diagrams became key.

Tracing the affected network showed that the Trailer Tow Module was the only other module sharing that section of the network. After removing the step to access it, the cause became pretty obvious from the condition of the module and connectors.

With the Trailer Tow Module disconnected:

CAN network voltages returned to normal
Communication stabilised
HVAC operation returned immediately

The actual fault was therefore not the BCM at all, but a £145 Trailer Tow Module dragging the network down.

That is exactly why control modules should never be condemned without proper testing first. On a modern vehicle, a fault in one module can affect multiple systems elsewhere on the network and easily lead to the wrong component being blamed.

Diagnosis carried out using:

Power and ground verification
CANBus voltage testing
Wiring diagram analysis
Network isolation
Module elimination testing

A much better result for the customer than replacing a BCM unnecessarily. ✅

LF Auto Electrics
Automotive Electrical Specialists

🔐 Pandora offer: We’re currently offering 10% off Pandora vehicle security systems. Get in touch for details.

Another very common fault sorted ✅

This Skoda Octavia came in with a number of broken wires in the door wiring loom. With the loom constantly flexing every time the door is opened and closed, these wires can eventually fatigue and break — causing all sorts of intermittent or completely dead electrical faults.

We stripped the loom back, identified the damaged wiring and carried out the necessary repairs to get everything working properly again. We keep the terminals for most doors wiring harnesses in stock!🔧⚡

If you're having problems with central locking, electric windows, mirrors, speakers, warning lights or other door-related electrical faults, it may be more than just a faulty component — the wiring itself could be the culprit.

We also offer a mail in service, where you can send your wiring harnesses in to be repaired. Get in touch for more information!

📍 LF Auto Electrics
⚡ Automotive electrical diagnostics & repairs
🔧 Fault finding, wiring repairs, diagnostics and more

And don’t forget — we’re currently offering 10% OFF Pandora security systems booked in September. 🔐🚗
Get in touch for more information or to get booked in.

⚡ This is exactly why proper diagnostics matter. ⚡

This Skoda Superb came in with a suspected steering control module fault and a new unit ready to be fitted and coded.

But after installation, the problem remained — so we dug deeper. 🔍

What we found:
❌ No communication with the steering column control module
❌ No communication with the BCM / central electrics
❌ Door locks continuously attempting to operate
⚠️ Faults pointing towards an issue on the comfort CAN network.
⚠️ Scoped the CAN to see any issues in real time
✅ Seen message interruption.

The culprit?
A faulty aftermarket trailer module interfering with the vehicle network.

Once removed and returned to factory wiring, communication was fully restored. Even better — the original steering column control module was refitted and worked perfectly, meaning the customer’s initial suspected part was not actually faulty. ✅

No guesswork. No unnecessary parts. Just the real fault found.
That’s the value of accurate auto electrical diagnosis. ⚡

📣 **Horn fault found — and a costly replacement avoided.**

This **Renault Twingo** had an unusual fault: the **horn became inoperative when the indicators were used**.
After proper fault-finding, the issue was traced to a **broken wire inside the left stalk**.

A new stalk would have been **£195 + VAT** — but instead of replacing the whole unit, the wire was **carefully repaired**, getting the horn working again and **saving the customer money**. ✅

**Unusual fault. Smart fix. Real savings.**
That’s what proper diagnostics can do. ⚡

🔋 **Battery drain found — and it wasn’t the battery.**

This **Citroën C4** came in with a parasitic drain concern, so we carried out proper testing to find out exactly what was staying live.

⚡ **2.5 amp drain traced**
🔎 Fault narrowed down to an **aftermarket tow bar electrical control unit**
📞 Customer contacted with our findings
✅ Unit removed on instruction, as the tow bar is no longer used

A 2.5A drain will flatten a battery in no time — this is why accurate fault-finding matters. No guessing, no unnecessary parts. Just the cause found and dealt with.

**LF Auto Electrics — Automotive Electrical Specialists.** ⚡

⚡ **Ford C-Max charging fault diagnosed and repaired** ⚡

This C-Max came in with the **charge warning lamp illuminated** and a charging system fault present.

Initial checks found:

❌ **No LINbus communication** to the alternator
❌ **No control voltage** present
⚠️ **Battery/charge lamp illuminated**

After tracing the circuit back, the cause was found to be a **broken alternator control wire** within the loom.

The damaged section was repaired, communication restored, and the charging system was back operating as it should. ✅

A good reminder that not every charging fault means the alternator itself has failed — proper testing saves unnecessary parts replacement. 🔍

📍 **Vehicle trackers supplied and fitted** 📍

Whether it’s for **added peace of mind on your personal vehicle** or helping to **protect and manage a fleet**, we can help with professional tracker installation.

Trackers can offer:

✅ Live vehicle location
✅ Movement and alert notifications
✅ Journey and usage visibility
✅ Added protection in the event of theft

We welcome both **personal customers** and **fleet operators**, with **volume pricing available for multiple fleet vehicles**. 🚗🚐🚛

Get in touch to discuss the right tracking solution for your vehicle or business.

Something a little bigger today, MAN TGL with EVS and ESP lamps illuminated. Wonder why? All because someone hasn't cables tied the wiring properly and it's been chaffing. Quick repair and it's on its way again!