V70 climate control backlights

Mountainman45 · Post by **Mountainman45** » 07 Nov 2019, 06:13

So I recently purchased a 2001 V70XC and while driving the other day I noticed that the passenger temp dial and the middle selector weren't illuminated. While this isn't the biggest issue I've got with the car as a whole, I do most of my driving at night. So as anyone would, I went to my local pull a part junkyard and pulled the lights out of another module ( I figured the chances of me getting a few good bulbs were pretty high). I installed them but no joy..... Every other light on this module works so I'm not sure what my issue could be. Any ideas/ solutions.

Post by **volvolugnut** » 07 Nov 2019, 10:15

Test the used bulbs with a battery to confirm they are good. Assure there is no corrosion or damage to the connections on bulbs or the climate module. Might be a problem with the module connector block pins. Take a good look at the connector pins and sockets when you have it apart.
volvolugnut

Post by **ljsommar1** » 07 Nov 2019, 10:52

Sounds like typical DIM issues that affected early P2 models. Read up on it. There are many repair services available.

Post by **firstv70volvo** » 07 Nov 2019, 19:17

This is interesting, why just the two lights are not working when there are 6 bulbs backlighting the panel. I would think power and ground to the 6 bulbs would be common so why just the two lights not working. You've replaced the two bulbs and still not working so it's possible something wrong with CCM circuit board but some things to recheck to be sure.

The only reasons bulbs would not work is if bulbs are burned out or power or ground not reaching the bulbs. As mentioned check the bulbs with a 12V power source or DVMeter before installing to be certain bulbs are good. I've included some photos to show the bulb locations in question and the wire that contacts the traces on the circuit board. I've had to bend the socket wire some to make a good contact with the traces on the circuit board. This is just getting under the wire and bending it up some to make the connection more snug when the bulb sockets are twisted in place.

If bulbs are known good then check the traces on the on the circuit board with the bulbs out. Do they look okay? Clean traces, socket wires and adjust(bend) bulb socket wire to make a better connection, see photo.

A more thorough check would be to pull the CCM out of the car, remove all bulbs and measured continuity of power and ground between non working sockets with working sockets. From past experience with LED lights and one way polarity the ground is the south east trace of all sockets and power is the north west trace for all sockets. I would expect continuity between power and ground traces for all sockets although I've never actually confirmed this continuity measurement myself. Please read about the proper procedure to remove CCM module to prevent expensive damage to the module. Never disconnect or connect CCM with battery still connected. Wait the required time after ignition is off to disconnect the battery. Be careful not to damage the expensive CCM when doing any work suggested.

FYI, The 2 white base bulbs are 100ma grain of wheat bulbs, which are easy to find so cheap to replace. The 4 gray base bulbs are 150ma grain of wheat bulbs, which are difficult to locate. I used super brite LEDs for replacement, which work great but can only be installed one way due to polarity so the polarity of the socket connections must be identified before install.

Mountainman45 · Post by **Mountainman45** » 08 Nov 2019, 08:00

Where did you buy your led lights

Post by **firstv70volvo** » 08 Nov 2019, 09:46

Mountainman45 wrote: ↑08 Nov 2019, 08:00 Where did you buy your led lights

T4 neo wedge type
http://www.autolumination.com/instrumen ... _bulbs.htm

I used this particular type but it looks like they also have other types now; wide angle lens, Japanese OEM, etc. Tall ones will likely not fit so use the shorter height versions.
http://www.autolumination.com/automotiv ... d_bulb.htm

Used 2 red (temp dials) and 4 white lights. I first hooked up each light to 12V to find polarity and then marked ground wire of each socket. When installing in back of CCM the ground trace is the lower slightly right one and consistent across all locations. Originally used a couple of blue lights (see picture) for cold side of temp dial but later changed those out to white lights.

Post by **ljsommar1** » 08 Nov 2019, 13:18

When I was having problems with my DIM, one of the first problems exhibited was missing the backlighting of one or two of the gauges and the high beam indicator.If I hit the dashboard they sometimes resumed functioning. I am not saying it has to be that but I did experience very similar symptoms. I sent my DIM out for repair and it has been working fine since.
I had tried to attempt a repair but failed to completely fix its issues.My attempts at repair included a heat gun and soldering. I got mixed results. One guage started working consistently but many others functions got worse.Surface mount technology boards are touchy to repair with conventional techniques.