91 740 Radiator Fan on high

[blynx]

I just replaced my speedometer with one from a pick your part on my 1991 740. It came from a 1990 740 and works well other than the miles on the odometer being different. However, after putting everything back in, I start the car and notice that the radiator fan is running on high, or it seems to be extremely loud. Could I have messed with something on the instrument panel and accidentally caused this? It stays on high if the key is in the II position or even when the car is cool from starting.

Thanks in advance.

[billofdurham]

Welcome to Matthew's Volvo Site.

I have attached wiring diagrams for the '90 and '91 instrument clusters. A careful check will show that the wiring differs in some parts - especially for the wiring coming from the temp gauge. On the '91 that wiring comes from A7 & A8. On the '90 it comes from B4 & B7, which will be causing the ECU to think that the coolant fan needs to be running.

740 '90 and '91 instrument cluster wiring diagrams.pdf

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Bill.