Need help with strange electrical gremlin

[Novicemechanic2002]

This is a wierd case, and i can find nothing online. These are a few seemingly unrelated problems that all started at the exact same time

-when opening the door, the light on indicator bulb stops burning, there is no lights on warning when lights are on anymore

-domelight does not work anymore, when put in alsways on position thesame indicator light stops burning again

-the tachometer stays at thesame rpm the engine had when the car was shut off. It just stays at 900rpm untill i put the key on electricals on position, then it drops to zero. Tachometer does read accurately when driving

What could this problem be? I thought maybe a broken door adjar switch, but i checked it and it works fine. Maybe a broken ecu port/output? 12v switched output? I dont know, please help

 

[Novicemechanic2002]

Forgot to add, its for an Aygo from 2011

[Mjolinor]

First thought ( and easy to check) would be damp inside.

Look under the carpets.

[Novicemechanic2002]

9 hours ago, Mjolinor said:

First thought ( and easy to check) would be damp inside.

Look under the carpets.

No damp or water anywhere in the car

[Bper]

Hi Michael,Since these issues started at the same time, the root cause is likely something common to all the affected systems. Start by checking the easiest components like fuses, relays, and ground connections. If those are all in good condition, move on to more components like the wiring harness or BCM. 

[Mooly]

This kind of reminds of a problem I had on an Audi. Seeming lots of unrelated issues (wipers would come on by themselves, fuel gauge reading low, warning lights at random, washers had little power to the jets of water) and the cause was a bad earth (loose bolt) on the passenger A frame where quite a few ground wires terminated.

This is a Toyota though and they don't normally have strange issues. The rev counter thing is very strange indeed as that is more electronic based and ECU driven. 

You have to start somewhere... check the Battery terminals are secure and even if they are I would disconnect the Battery and reset everything. 

16 hours ago, Mjolinor said:

First thought ( and easy to check) would be damp inside.

Damp might well be a factor if it has affected anything electronic. I don't know where all the electronic control units live in an Aygo but there will be several dotted around both in the car and under the bonnet.

Any history of work done or damage repaired even if it was a while ago?

Have you had the car a long while or is it recent to you?

 

 

[Novicemechanic2002]

3 hours ago, Mooly said:

This kind of reminds of a problem I had on an Audi. Seeming lots of unrelated issues (wipers would come on by themselves, fuel gauge reading low, warning lights at random, washers had little power to the jets of water) and the cause was a bad earth (loose bolt) on the passenger A frame where quite a few ground wires terminated.

This is a Toyota though and they don't normally have strange issues. The rev counter thing is very strange indeed as that is more electronic based and ECU driven. 

You have to start somewhere... check the battery terminals are secure and even if they are I would disconnect the battery and reset everything. 

Damp might well be a factor if it has affected anything electronic. I don't know where all the electronic control units live in an Aygo but there will be several dotted around both in the car and under the bonnet.

Any history of work done or damage repaired even if it was a while ago?

Have you had the car a long while or is it recent to you?

 

 

Ive had the car for half a year, recently only did an oil change and put in a better head unit. Head unit was a month prior to issues arrising, and is confirmed working in another car

[flash22]

Check the dome fuse and the fuses around the gauges

the rev counter is 5 wires 12v, 12v sw live, ground, illumination and a rpm signal

only thing in common is the dome fuse,  - poor wiring on the radio may be a factor if it's been cut instead of an adapter being used

[Mooly]

1 hour ago, Novicemechanic2002 said:

Ive had the car for half a year, recently only did an oil change and put in a better head unit. Head unit was a month prior to issues arrising, and is confirmed working in another car

Thanks. Fault finding is all about gathering evidence and knowing the history can be useful in piecing things together. It may well be a good idea just to backtrack over any wiring changes that may have been made if only to eliminate that as a possible cause.