12 Jul 2024
The voice of the independent garage sector

A month in the life of a vehicle technician

The last topic concluded with a promise to share my experiences working within a workshop lacking in essential infrastructure. I hope by explaining my failings and limited success, it helps identify the importance of correct process, correct tools and comprehensive systems information. If you forgo one or more of these three critical elements, failure is predictable even before you begin a repair task.
    
The most basic and simple error; Failing to assess the battery rating and cell condition. Note I didn’t focus simply on voltage. The first example was a Ford Focus 1.6 ecoboost, suffering windscreen wiper failure. The car was driven to us, and the customer explained the battery had gone flat and been charged.

Conductance test
I began with a conductance test with my personal Midtronics MDX 600. Voltage was 12.47, rated 540 amps, however it only returned 346 amps. Please refer to Fig.1. I ordered a replacement and decided to continue testing the screen wiper problem. The vehicle started and drove into the workshop, so I began checking voltage and ground at the twin wiper motors. There was no change of state, however the voltage was below 9 volts after only a very short time. So, I fitted a temporary good battery and continued with my tests, only to find the wipers working normally.
    
The explanation is straightforward; CAN and lower priority networks often hibernate with system voltage drop. So, my knowledge, process and tools won the day here. The next problem, another Ford Focus, had much more challenging issues. Initially it drove to us with starting problems, then failed to start.

Global vehicle check
I began with a global vehicle check using the garage TOPDON serial tool. It had reasonable systems access and displayed steering column communication loss with the body control module; B1026:87-2F. It showed two keys stored, and the immobiliser was registered in the PCM. We had limited wiring access via E3 tech data, but crucially no test plan data. We were dead in the water now, relying on the common-sense method. We decided to ramp the vehicle and examine wiring and PCM, located we thought under the front wheel arch.
    
The PCM housing was damaged, probably from a light frontal impact, and had allowed water ingress. The next series of events taken over several weeks is a textbook example of how to fail in a repair and diagnostic process. My only satisfaction was that the decisions were not of my making.
    
The cost of a  new PCM with programming and coding exceeded £1,500. The owner could not afford the repair, so a second-hand PCM was suggested. Mistake number one; Cost must never influence correct process.
    
A unit was sourced by the owner in Poland. Mistake number two: Never allow customer interference in the repair or part procurement process. The owner was instructed to send the original PCM to Poland so programming and coding could be transferred across. Mistake number three: Never use or trust third party contractors unless personally known to you. Although this is technically possible, and we at ADS have done this many times, you have now lost control of the repair. This mistake is fatal and has no comeback.
    
The PCM was fitted to the vehicle and guess what? No change in the symptoms. I was then re-tasked to check the fault from the sketchy wiring schematics. I had no enthusiasm left at this point, so let’s score it as mistake number four; You need to have a positive mental attitude. My evening’s Vodka consumption didn’t help. Having exhausted all limited direction of diagnostic enquiries, it was time to put the train back on the tracks.
Please refer to Fig.2.
    
I consulted a local friend and expert, Paul Emmett from Reedley Service Centre. This was correct decision number one. He owns the Ford IDS platform, with which one can programme and code the PCM. Following this process, the keys operated the central locking, and the instrument cluster became active. Despite this apparent progress, there was still no cranking. As part of the coding process though, a global scan was conducted, resulting in a curious and previously unknown error. It turned out that both rear wheel speed sensors were defective. Paul suggested replacing them before continuing; Correct decision number two. The sensors were replaced, and the vehicle started normally with all stored codes cleared. I place this explanation in the same column as my previous observations. In short, wheel speed sensor errors are broadcast on high speed CAN, therefore the error frames must have corrupted the network, thus preventing crank start.
    
The failure to understand this I put down to incomplete serial data from TOPDON.
    
I am sure I don’t need to recap events, and I am not going to expose the decision makers, but as the technician in question I should have refused to continue. This was mistake number five. I don’t know what the owner was charged for the repair, but I hope it was more than the original estimate.

Challenges
Let’s end on a little restored personal pride; A Ford Transit Connect with a faulty power steering assist system was presented, with a blown 60amp control fuse for good measure. Challenge number one; Ford would only supply a complete vehicle wiring harness for £600 despite the auxiliary fuse panel being easily replaceable. Please refer to Fig.3. I decided to replace the fixed fuse assembly with the correctly rated value and conduct current flow analysis by logging serial data and directly using my personal fluke clamp. Current peaked at 65amp for a few milliseconds. Average current flow was 35amps. Please refer to Fig.4.
    
I was made aware of known issues with steering rack faults, and I am waiting to see if the fault reoccurs, which will mean  a new rack assembly is required. This customer has no issues with cost.
    
I have archived many examples of good and challenging decisions facing technicians with limited access to essential assets. More next issue.