My son is convinced that my Volvo is not going into overdrive and I am convinced it is, is there a way of convincing him it is?

As volvofromheck states, accelerating with plenty of throttle (say, about half - no need for full throttle) should let you feel firm upshifts from 1-2 then from 2-3, and when you ease up on the pedal, a shift into 4th (overdrive) with a significant drop in engine RPM (watch the tach). If you then hold a steady speed, you should very soon feel what seems like another "shift", as the transmission locks up (torque converter clutch engages) and RPM will drop by about 300 RPM.

I don't know for certain, but I don't think the lockup will occur unless the trans is in 4th/OD. Another way to tell if OD is operating is your engine RPM at 60 MPH...it should be about 2200 if the trans is in OD and lockup, around 3100 RPM in non-OD 3rd.
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Bob: Son's XC70, my 83 244DL, 89 745 (Chev LT-1 V8), 98 S90 (recently sold) and XC60. Also '77 MGB and four old motorcycles

If you have manual transmission, you have a "5" idiot light on the cluster.
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Post Back. That's whats makes this forum work.

Not having a manual tranny there is no idiot light on the cluster!!

WRONG,,auto trans always have the orange arrow on the cluster.

Flacito wrote--"Not having a manual tranny there is no idiot light on the cluster!!" Not so I believe--there should be an "upshift" light (an upward facing arrow? -- at least on a 240) on the dash if you lock out the OD. Have you always owned this car? Maybe a previous owner modified the solenoid or installed a bypass kit to always have OD. -- Dave

Dave wrote: "Maybe a previous owner modified the solenoid or installed a bypass kit to always have OD."

What can you tell me about the "bypass kit" that you mention? The orange upshift light on the dash sometimes appears by itself (no buttons pressed), and I'd like to eliminate it and always have overdrive available.

- Bill

Here:

https://www.ipdusa.com/products/4793/110397-automatic-over-drive-solenoid-bypass-kit

-J
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1982 242Ti, 1985 245Ti, 1992 245GL

Thanks! Sounds like I need one of these.

You can accomplish the same thing for no real cost by removing your solenoid and grinding a groove between the inner and outer ports - examination will make it obvious what needs to be done. Art's "clean flame trap" probably describes the mod. -- Dave

Yes (are we talking automatic?) -- drive to a steady highway speed and then use the OD lock-out switch - the transmission should downshift with a rise in the engine rpm. If that doesn't work because maybe the solenoid, switch or its wiring is bad and the engine rpm stays the same--stop the car and accelerate briskly (floor the throttle) -- with a hard throttle the shifts should be easily noticed -- 1,2,3 and then level off the speed and you should detect the shift to 4th (OD). -- Dave