240 auto kick down light + Fuel and temp guages HELP please
 

Hi,

1990 240 GL auto estate. (107K miles).

Need help before digging deep into the cars wiring:

Went for the kick down button and suddenly both fuel and temp gauges died completely and the kick down indicator lamp underneath started working in reverse: Light on - regular gears, light off - kick down engaged.

So far I've tried

1. Replacing the auto kick down relay - no change
2. Replacing the voltage regulator transitor for the fuel and temp gauges (located on the back of instrument circuit panel). Ok for 10 minutes then back as before
3. Disconnecting the fuel sender at the tank end. This got the temp gauge working again but still intermittent. Also the 'kick down' light still comes on at random - low glow.

Before going any further wondered if anyone out there has had a similar exeperience or knows the true fix. Next stage will be working through the wiring and swiches on the auto box by elimination- not straight forward.

So any sound advice greatfully recieved. Thanks.

I don’t have an auto and haven’t experienced or heard of the same symptoms as you’re experiencing - but it sounds like an loose earth somewhere to me, possibly near the or connected to the kick down button since that started the whole episode...

Sorry that isn’t much help!

Cheers

Now I'm intrigued! I've had many cars with auto boxes-including a 144 and a 245-and I can't recall any of them having a kick down button[except the switch a the loud pedal] or light.For kick down I've always just mashed the loud pedal into the carpet the gearbox has then dropped gears and taken off before working its way back up the gears.I've had them[still have one]with a sport mode button on/near the selector which does have a corresponding dash cluster light,but that doesn't kick down the gears just holds on to each gear for longer in the rev range.

Kick down button => overdrive button?

No experience with this fault, sorry. Happy day, Kay

Yes - it is the over drive button -on left side of the gear stick top. Will do an earthing check on that end of things first.

Many thanks.

Graphic

Are the o/d switch/light and the two gauges on the same fuse? If not it might help eliminate the problem if the two gauges work independently of the o/d switch when the o/d switch fuse is removed

I agree with Bugjam that given the fault occured when the switch was operated, that would be where I'd start - it may be as simple as a wire tag coming adrift

Good luck with it

Like my right honourable friend Nick, I don't have experience of auto issues. I am confident someone with such experience will arrive in this thread. I hope.

From general experience and recollections upon previous issues in the forum.

1. Is there an earth fault?

2. Is the kick down cable faulty or damaged?

Thanks chaps,

After another 2hrs of methodical checking, here's how it stands:

Overdrive circuit is on the same fuse as the rear window heater (?). Pull fuse - nothing works. Fuse in - O/D electrics OK. Problem with gauges and OD indicator lamp still persist.

Wiring checked on gear shift - inc the 'allow start' on P and N - all OK. Earthing is OK.

Rear floor up - All wiring to the fuel sender unit Ok. (Well impressed with how secure they made all the wiring in this area).

Fiddled around with the voltage regulator transitor on the back of the dash circuit board (nice of volvo to put it in a socket, not direct soldered). Connected - some response on the fuel gauge - not right down, but the OD lamp lit the whole time. Pull the transistor - OD lamp goes out. fuel gauge right down.

So ... either the voltage reg. transistor socket or possibly the dropping resistor that feeds a control voltage to the trani failed ? Will check this next go.

Learned a lot but out of time for now. Its drivable - Overdrive works and the lock off switch ( side of the top of the gear shift) works. Just v inconvenient wit no fuel or temp gauge and the OD lamp on all the time.

Like Stephen, I am a manual man (!) so I cannot speak about the specifics of the auto set -up. Just that this must be a simple electrical fault (regardless of the transmission type)...
Graphic will you let us know the outcome - please?

Also, dum question, but what happens when you pull the fuse for the two gauges - does that have any impact on the O/D operation or light?

Thanks for the interest Nicolas.

The OD arrow lamp (far right in the display) goes out completely when the fuse is pulled.

Seams some 'cross talk' going on the instrument circuit board: My best guess - the voltage reg dumps current down the same earth that the OD lamp is on, so creating a voltage accross the OD lamp - & the lamp lights.

Next step - check that resistor with a multimeter.