Delayed shift to overdrive on 1990 Volvo 740

When i get on the highway, it takes about 20 to 30 minutes driving before the car goes to overdrive, so if I'm running the engine at about 3200 to 3500 RPM for that long is that a problem besides poor gas mileage? Is there any obvious/inexpensive fix for this problem?

Asked by for the 1990 Volvo 740
The first thing I would check is the transmission fluid level and the kick-down cable. Also, verify that the overdrive relay is functioning properly. All these are common issues that any Volvo mechanic would be familiar with.
1 more answer
Hi, I had same problem on my 1990 740. The issue was solved by changing the overdrive switch "as I was told the name". The older one was a little short to make electrical contact to detect 4th gear position & enable overdrive circuit to complete