Soooo. After relentless attempts of solving the issue of engine light flashing resulted in limp mode being activated, 3 garages trying different things to no avail! I had a Mercedes’ specialist let lose and after changing the boost pressure sensor and then noticing there no power going to this, he took the plugs of ecu and hardwired to the sensor and got a current so Diagnosed it as a faulty ecu? My question is two things… would the ecu stop sending signals to this said sensor while it’s in limp mode and that’s why there’s no power? And if this is a faulty ecu what would be the best solution to the fix? New ecu is going to be expensive, and I’m under impression a second hand one would not work by simply swapping it over?
Over boosting issue. Faulty ecu?
- Thread starter Jj86
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- 2022 Hyundai IONIQ 5 RWD / 2016 Suzuki Vitara AWD
Can't help with the diagnosis, but if the ECU does need replacing, you can try these guys:
www.bba-reman.com
Home (GB) | BBA Reman
ABS, ECUs, Power Steering, Throttle Bodies, Sat Nav and I.C.E, Instrument clusters From stock or your faulty unit rebuilt with a LIFETIME WARRANTY
Supernoodle
Active Member
Not sure what this error is as you don't say, but can some info on how Ecus work.
I assume the pressure sensor is the normal 3 pin analog device. There will be three wires, power (5v), signal and ground. The signal is from the sensor to the ECU. The signal will be voltage 0.5-4.5v. Inside the ECU that signal pin will be pulled up to 5v or down to ground 0v. That's why the working range of the sensor is away from the 0 and 5, so it can detect open and short circuit. If you measure the signal pin with sensor disconnected at 0v, chances are it's pulled down(most common on 3 wire devices) . It is not necessarily faulty.
The 5v will be permanent, ECU does not disable this. The ECU will have multiple 5v supplies, normally 3.Each will power multiple sensors. So if you have a bad 5v supply you will lose other sensors too. You should get a sensor supply fault code too as their output is monitored.
If you wanted to prove a point you can "borrow" a 5v from another sensor.
I'm not sure what statement got a current so diagnosed as faulty ECU meant.
Most electrical faults are continuously tested by ECU, not just engine running or some other special condition. They also go straight to defect, they won't go pending like a plausability fault. So it's quite possible that you delete the fault code and it comes straight back so appears not to clear.
I would find a decent auto electrician if you're down to poking around with signals before condemning ECU.
I assume the pressure sensor is the normal 3 pin analog device. There will be three wires, power (5v), signal and ground. The signal is from the sensor to the ECU. The signal will be voltage 0.5-4.5v. Inside the ECU that signal pin will be pulled up to 5v or down to ground 0v. That's why the working range of the sensor is away from the 0 and 5, so it can detect open and short circuit. If you measure the signal pin with sensor disconnected at 0v, chances are it's pulled down(most common on 3 wire devices) . It is not necessarily faulty.
The 5v will be permanent, ECU does not disable this. The ECU will have multiple 5v supplies, normally 3.Each will power multiple sensors. So if you have a bad 5v supply you will lose other sensors too. You should get a sensor supply fault code too as their output is monitored.
If you wanted to prove a point you can "borrow" a 5v from another sensor.
I'm not sure what statement got a current so diagnosed as faulty ECU meant.
Most electrical faults are continuously tested by ECU, not just engine running or some other special condition. They also go straight to defect, they won't go pending like a plausability fault. So it's quite possible that you delete the fault code and it comes straight back so appears not to clear.
I would find a decent auto electrician if you're down to poking around with signals before condemning ECU.
There is more chance of it being wiring than an ECU.
Continuity does no guarantee a good wire, putting 12v down the wire is a better test.
You could get continuity on all three wires even if they had fused together.
I agree an Auto electrician is a better bet.
You generally find the wiring fault after the ECU hasn’t cured it.
Continuity does no guarantee a good wire, putting 12v down the wire is a better test.
You could get continuity on all three wires even if they had fused together.
I agree an Auto electrician is a better bet.
You generally find the wiring fault after the ECU hasn’t cured it.
