Volvo Repair: Volvo 740 GLE wagon 3rd gear downshift stuck, volvo 740 gle, electronic circuit boards

Question
QUESTION: Hi Roger, What a neat service.

I just came back from overseas doing emergency response work. a terrific family gave me an '89 Volvo 740 Wagon. I am crazy about Volvos so was thrilled. But, as wonderful as that 2.3L engine is, and the comfy leather seats, the auto transmission keeps spontaneously shifting into the 3rd gear (button on the shift lever untouched). It gets stuck there as I am driving from Boston to Haverhill on the interstate. That means a long slow trip keeping the RPMs under 2500. I have tried everything. . . never know when it will happen, city or highway. My smart son says disable the thing. Is there anything I can do? How does one disable the feature?

Thanks a million.

LCC

ANSWER: Lucia, Check the overdrive relay. I have seen this happen before.  Its behind the ashtray assembly.  Its the skinny white relay.  Roger

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QUESTION: Can you tell me what I need to do with the relay if it has gone bad? Sorry, I just don't know what it is and could use some "how to". Thank you for your answers.

Answer
Lucia, there really is no way to check it unless you know electronic circuit boards.  You can check the fuse for the overdrive first and see if its okay.  I would just replace the relay.  Its a common problem.  Remove the ashtray assembly, remove the cover to the cigarette lighter, behind that will be 2 screws.  Remove the screws and that panel comes out.  Now you can see the relays.  Tall skinny white one on the right side.  Roger