colling fan and temp sensor problem on 2000 Volvo S70

check engine light came on indicating problem with cooling temp. sensor. Fan started to stay on even when engine cold and Temp gauge shows car overheating even when engine cold. Replaced Fan relay, cooling temp sensor and thermostat. Same problems. Told it might be computer gone bad and may need to rebuild. Any suggestions.

Asked by for the 2000 Volvo S70
Before condemning a bad ECM you will want to make sure the wiring is OK.
Don't want to spend $1500 on ECM. Car only has 123K miles. But can you tell me what wires would cause this problem. And really appreciate the help.
If you want to do this you'll need a wiring diagram, an ohm meter and some basic electrical knowledge and electrical circuit troubleshooting skills. I cannot coach you through this here, it's too technical. My feeling is that if you have to ask this question, you are not likely able to perform these tests properly.
You are best to find a good shop and have them diagnose this. Look for a Bosch Service shop in your area.
Hey guys thanks for your help. Discovered problem. Napa sold us a bad cooling temp. sensor and that was causing all of the problems. Replaced with dealer part and all problems fixed.
1 more answer , 1 more comment
if the wires from sensor to pcm is shorted that would do it.
Thank you for your reply. Can you tell me what the pcm is and how to test wires if they are shorted?