I have searched and read many of the Transmission Overdrive threads and have not found an answer to my situation so, I am asking the question.
I have a '89 Volvo 245 wagon that is completely stock.
Everything worked as it should including overdrive. After a few years of driving well, the transmission recently stopped going into overdrive. Fluid is full and clean.

I can hear and feel the overdrive relay click. I have voltage to the overdrive solenoid under the car when the gearshift overdrive selector switch is off and the instrument cluster arrow light is off.
I have no voltage at the solenoid when the gearshift overdrive selector switch is on and the instrument cluster arrow light is on.
Both if these are normal conditions.

I tested current of the overdrive solenoid on the car and found that with the battery at 12.5V, a resistance of 13.7 ohms on the wire through the solenoid to ground, I had a solenoid current draw of 0.93 amps with the switch in the off (energized) position. Of course I had no voltage/current at the solenoid with the switch in the on (deenergized) position.
I removed the solenoid applied compressed air to one of the two solenoid ports (no air flow) and then applied switched 12 volts to the solenoid. The compressed air flowed through the solenoid with the switch closed as would be indicative of a properly working solenoid.
I went as far as to replace the relay and solenoid with new, known good, devices and still no upshift to 4th gear.
I have concluded that there must be a issue inside the transmission preventing overdrive engagement.

What in the transmission controls the overdrive clutch? and how is it serviced?
Thank you.

 

Here's what Volvo has to say
http://www.240.se/litteratur/tp30868_2.pdf

 

[QUOTE=Xoloski;496015]I have searched and read many of the Transmission Overdrive threads and have not found an answer to my situation so, I am asking the question.
I have a '89 Volvo 245 wagon that is completely stock.
Everything worked as it should including overdrive. After a few years of driving well, the transmission recently stopped going into overdrive. Fluid is full and clean.

I can hear and feel the overdrive relay click. I have voltage to the overdrive solenoid under the car when the gearshift overdrive selector switch is off and the instrument cluster arrow light is off.
I have no voltage at the solenoid when the gearshift overdrive selector switch is on and the instrument cluster arrow light is on.
Both if these are normal conditions.

I tested current of the overdrive solenoid on the car and found that with the battery at 12.5V, a resistance of 13.7 ohms on the wire through the solenoid to ground, I had a solenoid current draw of 0.93 amps with the switch in the off (energized) position. Of course I had no voltage/current at the solenoid with the switch in the on (deenergized) position.
I removed the solenoid applied compressed air to one of the two solenoid ports (no air flow) and then applied switched 12 volts to the solenoid. The compressed air flowed through the solenoid with the switch closed as would be indicative of a properly working solenoid.
I went as far as to replace the relay and solenoid with new, known good, devices and still no upshift to 4th gear.
I have concluded that there must be a issue inside the transmission preventing overdrive engagement.



What in the transmission controls the overdrive clutch? and how is it serviced?
Thank you.[/QUOTE


Ok sometimes its the simplest things. Check fuse number 12. It controls many features including overdrive!
not much else controls this feature besides what you already did.
The transmission will focus fine with malfunctioned solenoid until 40 or 45 mph.
Goldenblock

 

Thank you for your response.
I did test the fuse but didn't mention it in my narrative as I thought it would be obvious that the fuse was good as I have voltage to the solenoid and current draw through the solenoid when activated.

My thought is the overdrive solenoid's fluid pressure engages a servo, which in turn activates a band, which locks up or releases a sun gear thus allowing 4th gear and that there may be a servo/band adjustment inside the transmission.

 

Thank you, I will read this.

 

Looked over the manual.
Found it interesting that the 3 to 4 gear upshift is listed as happening at 70 mph.

Inspected my kickdown linkage adjustment to find the adjustment reference ferrule crimped to the cable to be loose and sliding on the cable.
At one time I did replace this cable had the adjustment correct.
I do not think this adjustment could cause my issue of no 3 to 4 upshift.

 

mine shifts to 4th / OD at about 38 mph with light pressure on the throttle. when i had my issues
of no OD i replaced the solenoid,wiring, and relay and the trans still would not shift into OD. light on the dash was working normally on/off.
what cured it was running the car in gear on a lift for just a few seconds with the solenoid loose (bolts backed off a bit), tightening the solenoid back down
then replacing the lost fluid and cleaning up the mess. it's a last ditch method that worked in the end.
the pressure from the trans probably blew out an obstruction so OD worked as usual.

 

Thanks Silvermine,
I will recheck all of my previous actions and if I find the same results which I expect I will, I will definitely give that a shot.
Any idea which way fluid flows through the solenoid? I may try to reverse pressure compressed air in the trans.
Xoloski

 

which way it flows- nope haven't a clue. some folks do use a bypass plate though