Volvo Repair: Volvo intermittent transmission problem., throttle position sensor, 1992 volvo 960

Question
Dear Mr. Regis J Easler III,

My 1992 Volvo 960 has a problem of the orange up arrow light flashing. I took the car to the mechanic. He replaced a neutral sw, speed sd and a throttle sw. He informed me that it was fixed. I started driving home about 6-7 blocks and noticed that as I race the engine to 3-4 thousand RPM the car would not go. I called the mechanic and he said to tow the car back. Instead I turned off the engine, waited about 15 seconds, and the car started up like normal again. I just made it back to his garage. Please let me know you opinion and if you have any suggestions. I would greatly appreciate your response.

Thank you,

Narong


Answer
I had a car similar to this it was a 92 960 just diagnosed it 3 days ago.this car did have the arrow on and repeat codes even after checking wiring and the sensors it would say were bad the codes would still be there.it did not have a problem moving as you state yours had.if there are codes for a bad throttle position sensor,mode selector switch or kick down switch as mine did ,it turned out to be a bad fuel system control unit.this took quite some fault tracing to diagnosis this problem.the only way to be sure is to try a known good control unit in the car and see if it is ok.you can check all the sesnors and wiring and still not find the problem if it is an internal problem in a control unit.I hope this helps.let me know how it goes.