2004 XC90 CEM Turn Signal Issue – Right Side Stays On Constantly

[Matrex80]

Hello everyone,

I'm hoping someone here can help me with a strange electrical issue on my 2004 Volvo XC90 (CEM part number: 08688513).

The problem:
The right turn signal (front, rear, and side) stays on constantly and does not flash. It even stays on after I turn off the ignition and remove the key. The left turn signal works perfectly fine.

What I've tried:

1. I removed one of the black relays from the CEM relay block. When this relay is installed, the right turn signal works constantly (no flashing). When I remove it, the right turn signal stops working completely and the car returns to its original problem (right signal not working at all).
2. I bought a used CEM (same part number family) and installed it. With the used CEM, the lights work, but the car will not start because of the immobilizer (I understand the CEM needs to be cloned, which is very expensive where I live).

My questions:

1. Does anyone have a CEM connector pinout or wiring diagram for the 2004 XC90 that shows which pins control the right turn signal relay?
2. Is there a way to bypass the faulty CEM circuit and install an external flasher relay to make the right turn signal work normally again?
3. If I install an external flasher, which wires should I tap into (power, ground, signal from the turn signal stalk, and output to the bulbs)?
4. Has anyone successfully repaired the CEM itself? If so, what component usually fails (transistor, resistor, etc.)?

I have an EU inspection (EU-kontroll) coming up in 10 days, so I need to find a practical solution quickly. Any help or guidance would be greatly appreciated.

Thank you in advance.

[RickHaleParker]

Take the case off the CEM and look for shorts. It might just be that simple.

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Do you or a buddy have hot-air soldering station and know how to transfer chips without cooking them ???

The specific chip responsible for the turn signals and hazard lights is typically a STMicroelectronics VNQ830 ( or equivalent ).
The VNQ830 is a Quad-Channel High-Side Driver housed in an SO-28 (SOP-28) surface-mount package. It essentially acts as four independent, electronically protected solid-state switches in a single chip casing.

There are four (4) VNQ830 chips on the PCB. You will need to trace pins to harvest the correct one.

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Your immobilizer data, keys, and VIN are stored entirely on a single flash memory chip.The target component is the Intel 28F400 flash chip. It is a 44-pin TSOP (Thin Small Outline Package) surface-mount chip located on the lower main circuit board inside the Central Electronic Module (CEM).

You would get one shot at a memory chip transfer. Mess it up and then the only option is a expensive trip to a dealer. Go for the VNQ830 before you go this route.

[cn90]

Could this be from a bad wiper stalk?

[RickHaleParker]

Could this be from a bad wiper stalk?

The problem goes away when he swaps CEMs.