V70: Electrical Alarm disable?

[Tatsfield]

I never took the switch out as the penetrating oil did the job. Lazy man's mechanics! I've read that the latch is difficult to get at but the switch is easy to remove once you have got to the latch. Since your switch doesn't seem totally seized, the penetrating oil may well work and save you any dismantling.

[ShadeTek]

Originally Posted by ShadeTek

I take it the switch is buried inside the mechanism? Can it be opened up or drilled in to and some Deoxit fired into the moulding?

Your second picture with the connector. Where exactly is that on the car? I have a connector but it has three wires and they all read open cct to each other so I assume I am at the wrong one. They are +12vdc, ground and I assume a signal wire for something. According to the schematic, it should be two wires, BK-RD and BU-OG. One goes to chassis at point 31/96 and the other goes to the CEM.

[ShadeTek]

According to a well known bit of software available on the internet, the hood open sensing is not as simple as it seems.....
372: CEM-B10E901 Engine Hood Ajar Switch #2. General Failure Information. General electrical failure.

Diagnostic trouble code (DTC) information CEM-B10E901 Condition
This vehicle is equipped with a bonnet switch with two signal cables. These are connected to different inputs on the Central Electronic Module (CEM). One input is only grounded when the bonnet is open and the other input is only grounded when the bonnet is closed.

For the ERS function to be activated, there are several safety requirements that must be met, one of these is that the bonnet is closed. Therefore, the bonnet switch must have two signal cables in order to be diagnosed.

The diagnostic trouble code (DTC) is stored if the control module detects that:
Both inputs to the Central Electronic Module (CEM) are grounded.

Neither of the two inputs to the Central Electronic Module (CEM) are grounded.
The control module's test for the diagnostic trouble code (DTC) starts in the event of:
Ignition switch position II.

Note! The control module can only detect the fault once the test has been started and the diagnostic trouble code (DTC) is stored when the conditions are met.

Possible source
Connector resistance and oxidation in the connectors.
Short-circuit to ground on one of the signal cables from the bonnet switch.
Open-circuit in one of the signal cables from the bonnet switch.
Short-circuit between both signal cables from the bonnet switch.
Damaged bonnet switch.

Fault symptom[s]
EF, Engine Remote Start (ERS)/Does not work
KB, Alarm/Arming does not work/No visible indication.


I wonder if it is one switch with a double throw, or two switches, one for each latch mechanism, one pull-down and the other pulling up the voltage?

After much back-probing and voltage testing with the latches open and shut I got absolutely nowhere and I am perplexed. I think I will need to get the latch mechanism out to inspect it. I did grease up and soak the mechanism, but now the hood saying is saying it is permanently open on the dash. This could get interesting at 3 in the morning when the alarm goes off.

[Tatsfield]

Originally Posted by ShadeTek

Your second picture with the connector. Where exactly is that on the car? I have a connector but it has three wires and they all read open cct to each other so I assume I am at the wrong one. They are +12vdc, ground and I assume a signal wire for something. According to the schematic, it should be two wires, BK-RD and BU-OG. One goes to chassis at point 31/96 and the other goes to the CEM.

The connector is immediately to the left of the driver side latch seen when standing in front of the car. It's on the side of the headlight housing with the feed running back into the engine bay..

I cannot comment on how the system works but I do know that when I had the problem, the jumper across the two wire feed isolated the bonnet latch switch circuit and stopped the bonnet open warning which was permanent while the switch was jammed open.

[ShadeTek]

This is what I have. I'll wait for a good day and properly dismantle everything and have a look to see what is what in there. The diagram in Vida only shows a wire going to one lock mechanism.

[Tatsfield]

Different model, different system. Looks like my experience is not going to be of any help to you. All I can now say is dowse the switch in penetrating oil and hope for the best. Sorry

[Martin Cox]

Having now seen your pictures, I find myself in the same position as Tatsfield. My apologies if I've led you on a wild goose chase. it's obviously quite different to my 2008 V70.

Martin

[ShadeTek]

Originally Posted by Martin Cox

Having now seen your pictures, I find myself in the same position as Tatsfield. My apologies if I've led you on a wild goose chase. it's obviously quite different to my 2008 V70.

Martin

Thanks for the input, all is appreciated. The dash is now permanently displaying an open bonnet and red triangle but I noticed this morning when going over bumps on the road, the display would flicker on and off suggesting a bad contact. When I got back I got my son to sit in the car as I tapped around and on the drivers side catch and he said it was flickering on and off with the taps. Looks like it is the switch or wiring around there but if it is the 3 wire set up it may well be a hall effect type sensor as I read open circuit down all 3 pins of the switch, if that connector even does go to the switch it's hard to tell as it disappears. I'll need to find a newer schematic.

[Jimsmith44]

Just a thought have you tried dropping the bonnet from about 2ft? When my car shows that message i do it and it works as it has on all the Volvo's i have owned.

[ShadeTek]

I tried and it did work but yesterday I lubed the lock with spray grease which has made things worse.

I found a diagram for V70 2015 and it is exactly the same for the 2008 version I have with only 2 contacts coming from the switch on the schematic. I must have the wrong connector on the car.