The story began with the fact that our client turned off the car, went to the store, returned, the key to the start – and the engine does not start. What to do? How good it would be if you could call and the masters would come to you and fix the car! Demand creates supply – there are such services in search engines in our city. Our client was tempted by this, and masters came to him with a scanner.
When trying to start the engine, all devices behaved as expected, with the exception of a non-extinguished lamp of a regular immobilizer (a machine with a lock and key). We connected the scanner, but there were no errors in the memory of the engine control unit – this is an ambush where to dig, a dead end!
The comrades did not despair, they began to try to turn on the starter directly, having bridged the relay contacts, to supply voltages where they should not. As expected, there was no launch. And, in the end, their conclusion – “you have a problem in the immobilizer, perhaps the key has flown, erased from memory or something like that.” I wonder if the lamp didn’t burn, what would they say then? Diagnostics on departure costs from 500 rubles.
And here already not going anywhere – I had to call a tow truck. So the car was with us.
American cars in electrical issues cars are slightly different from the Japanese and European. The ignition lock has both 12 volt and 5 volt circuits, and already on its signal the on-board electronics unit (BCM) feeds the entire car through high-current relays.
But do not think that you know everything and you will never have such a situation, do not poke anywhere at random: you just have to open and open a catalog on this machine, open charts, examine the question, verification methods. The catalogs are in English, and this should not be a problem in diagnostics, as well as the language in the scanner menu so that there are no different interpretations, also in translation.
Yes, it took an hour and a half to study in front of the computer, but there were clues, a chain of actions was laid out, checks that should be carried out to find the cause.
And everything led us to the harness of the engine compartment, and there we were waited for by a frayed, rotten wire.
We coped with one problem. But as it turned out, it was not the end – the starter did not want to turn anyway. I will not hesitate: the problem was in the fuse box under the hood, where the starter relay is and where there were attempts to start the cars with on-site diagnostics.
Inside the unit is a multilayer board that cannot be repaired, and the relay control lanes are burnt and closed.
The result – a short circuit in the fuse box. And good luck that the engine control unit did not fail, because it is it who supplies power to the relay at the moment of turning the key according to permission from the BCM.
Please note: “Not like other cars.” Which was the fatal mistake that the life fuse block was standing for. Due to its high cost of living, we had to change the starter switching circuit.
This record would not have appeared if it were not for the frequent stories and complaints of our clients about on-site diagnostics and wasted money in 90% of cases. For example, another case: the Opel Zafira owner with a robotic gearbox twice called out on-site diagnostics, they made adaptations, read and erased mistakes, but the car still jerked when shifting gears. And just had to change (and do not forget to do it regularly) clutch release fluid. Do not do it this way).
People need to understand that the car is not a kettle, it cannot be repaired on the knee, and the scanner is not a diagnostics. Diagnostics – a complex of checks that allows you to accurately find the problem, it does not last 5-10 minutes.