Winfred, since were on the topic of Volvos...

[jjg43]

I was wondering if you can help. I have three problems. (1) My 93 940 is missing the button on the shifter to disable 4th gear. Sometimes the transmission is working as a 4 speed and sometimes it works as a 3 speed (when the upshift arrow displays). I have no way to turn 4th gear on when this happens and this can be a problem on the highway. I ordered the overdrive switch from the local dealer today and was wondering if this should fix the problem. Is there any other relays, modules, etc. that would cause this? (2) Also, when the transmission shifts into each gear it is smooth but it seems to be waiting to long to shift (higher rpm than normal I think). This happens even when I am lite on the throttle. I don't wnat to be driving this car at 4,000rpm all the time. Can anyone tell me why it would be shifting like this? (3) The car has a shakey idle and I am getting bad MPG. Last week I had the car inspected. The fuel filter was replaced, spark plugs are good, air filter is good, engine oil was changed along with the trans fluid and filter, and the rear was drained and filled. I know this engine should run much smoother and I should be getting much better gas mileage but I don't know much about these cars. I was going to go back to my mechanic but he doesn't have any openings for another week.

Any responses greatly appreciated.

Thanks,

Phil

[winfred]

the od problem is most likely the relay, the switch is just a momentary on and not a on off type of switch and in almost 8 years have not seen one die on it's own, it's easy to test the solonoid just shoot power to it, the wire is zip tied to the shifter under the car, sometimes the connection under the car gets loose/dirty.
crappy idle can be a few things, lately i've been seeing a lot of blown intake manifold gaskets on those motors, you can find that with a can of carb cleaner, spray everything down while running and when the idle gets better you've found the leak, i would clean the throttle body as it gets a lot of oil build up from the flame trap (volvos pcv valve).
ill post more when i have time on how to check a few other things

[jjg43]

the od problem is most likely the relay, the switch is just a momentary on and not a on off type of switch and in almost 8 years have not seen one die on it's own, it's easy to test the solonoid just shoot power to it, the wire is zip tied to the shifter under the car, sometimes the connection under the car gets loose/dirty.
crappy idle can be a few things, lately i've been seeing a lot of blown intake manifold gaskets on those motors, you can find that with a can of carb cleaner, spray everything down while running and when the idle gets better you've found the leak, i would clean the throttle body as it gets a lot of oil build up from the flame trap (volvos pcv valve).
ill post more when i have time on how to check a few other things

[winfred]

once the throttle body is clean make sure that the tps is making connection at the idel position, there will be a click and there should be connection between the center pin and one of the outers with the throttle closed, the other outer pin is for the wide open throttle map of the computer, to set the throttle plate remove or loosen the tps and back off of the stop screw till the plate starts to bind when you open it, then open a half turn and lock with the jam nut, set the tps so that it clicks as soon as the throttle is opened, now set the drum that the cable pulls on with the little ball/socket jointed link so that the drum is 1 or 2 mm from it's stop, it will be applying light closing pressure to the throttle plate. my favorite spark plug for the b230 motor is the bosch super WR7DC gapped to about 30. don't for to check out the cap and rotor, make sure the spring loaded button in the center of the cap is not bad.
check that out and let me know if it helps, that usually gets most of them back online, i am not out of tricks yet