Guides, wiring diagrams & fuse box locations
Everything we actually use and recommend in the workshop — how-to videos, wiring diagram sources, fuse box charts and fault-code references for UK vehicles. Based in Wolverhampton, working across the West Midlands and UK-wide by post.
Transparency & a small perk: every card below states whether the link is a referral link, has no referral, or gives you something for mentioning us. Where a site is marked Discount on mention, quote mancarcoding.co.uk when you contact us or the supplier and there is a surprise in it for you. We never mark a link as a referral unless it genuinely is.
How-to videos & training
Watch first, wire second. These are the channels and write-ups we trust for diagnosis, coding and immobiliser theory.
ManCarCoding Workshop Journal
No referralOur own written walk-throughs: ECU cloning, all-keys-lost, immobiliser fitting, component protection and remapping.
ScannerDanner (YouTube)
No referralDiagnostic theory done properly — voltage drop testing, scope traces and live fault finding. The best free electrical diagnosis training online.
Ivan / Pine Hollow Auto Diagnostics
No referralReal-world CAN bus, network and no-start diagnosis on modern vehicles.
Ross-Tech VCDS videos
No referralHow VAG coding, adaptation and immobiliser data actually work — straight from the tool maker.
MyAirbags / module repair how-tos
No referralAirbag, ABS and cluster module repair explainers — helpful background before a send-in job.
Fuse box locations & relay charts
Find the box, the fuse and the amperage before you probe anything. Never tap airbag, ABS, gateway or immobiliser circuits.
Fuse-Box.info
No referralFuse box diagrams and relay layouts by make, model and year — dash, engine bay and boot boxes.
Fastest free lookup for 'which fuse is the OBD port on'.
FusesDiagram
No referralPhoto-based fuse box locations with amperage tables — useful when the printed lid label is missing.
Fuse Box Diagrams (Autogenius)
No referralFuse assignments plus common symptoms per blown fuse.
Our fuse box finder
Discount on mentionOur own UK-focused fuse box location tool — plus we will confirm the exact box for your VIN free of charge.
Mention mancarcoding.co.uk when you book and we will throw in a free health check — a small surprise for using our guides.
Wiring diagrams & pinouts
Match diagrams by VIN build date and body code — not model name. Facelift looms differ far more than people expect.
Autodata
No referralSubscription wiring diagrams, component locations, torque and service data. The trade standard in UK garages.
HaynesPro / Haynes AllAccess
No referralWiring diagrams, fuse box charts and step-by-step repair procedures per model.
eLearn / Workshop Manuals archives
No referralFactory manual PDFs including circuit diagrams for older platforms.
Ross-Tech Wiki (VAG)
No referralThe best free VAG reference online — module coding, adaptation channels, fault code meanings and pinouts.
Genuinely proven: most VCDS coding answers on UK VAG forums trace back to this wiki.
BimmerPost / E90Post wiring threads
No referralOwner-verified BMW pinouts, CAS/FEM connector maps and retrofit wiring write-ups.
Vehicle data & fault codes
Official UK lookups and code references — do these checks before buying a used module or donor car.
Real scenarios, short answers
The questions we get asked most on the phone — answered the way we would answer them in the workshop.
My car is dead and I only have one key — where do I start?
Check the fuse for the ignition/immobiliser circuit first (see the fuse box section), then confirm the key battery and that the immobiliser light behaves normally. If the light stays solid or flashes rapidly, it is a data/coding fault rather than a battery — that is a key programming job, not a locksmith cut.
I bought a used ECU on eBay and the car will not accept it.
On VAG that is component protection; on BMW it is CAS/FEM/DME pairing; on Mercedes it is FBS3. None of them are fixed by 'resetting' the car. The donor unit needs virginising or the pair needs cloning to your original data. Always get the donor VIN from the seller first so you can check it is not blacklisted.
The wiring diagram I found online does not match my loom.
Nine times out of ten it is a facelift or market difference. Match by VIN-decoded build date and body code (for example Golf 7 vs 7.5, F30 vs F31), not just by model name. Ross-Tech and factory manuals are safer than generic aggregator sites.
Which fuse do I use for a dash cam or hard-wire kit?
Use an ignition-switched circuit rated close to the accessory draw, never a fuse feeding airbag, ABS, gateway or immobiliser. Fuse box diagrams tell you which are switched vs permanent live.
Can I do this myself with a cheap tool?
Reading codes and clearing basic faults, yes. Anything writing to immobiliser data, EEPROM or flash can brick the module — a bricked cluster or gateway costs far more than the job. If a guide says 'do not interrupt power', take it literally.
Stuck halfway through a guide?
We finish jobs other people start. Mobile across the West Midlands, drop-in at Wolverhampton, UK-wide by post for send-in modules and keys.