I recently installed an 850 radio in my 940 and think I may have incorrectly spliced the 940 harness wires to the 850 harness wires. All the backlighting in the radio stays on all the time, even when the radio is off. This may be causing an excessive draw on the power wire from the HL relay. I'm suspecting there may be a difference in the harness color coding between the 940 harness & the 850 harness.

 

Do you have wiring diagrams for either radio? If so, you could probably consult both diagrams to compare wire colors with individual functions of the wires.

If not, you could always take a look at the old radio and make a list of your own. Trace each wire color in the radio to find the function of the wires, then compare with the 850 radio you just put in. You wouldn't need to do that for all of the wires, maybe just the ones that appear to run to the backlight. That would be a lot of work though.

Does the radio work okay? If it does, measure the drain with (at your fusebox) to see if it the backlight is drawing enough current to cause problems. If it isn't drawing much and isn't killing your car, I'd say run with it for the time being.

Sometimes when I botch installs or wiring work, I just take everything apart, and put it back together. Usually fixes new issues.

 

What's my best resource on-line for a color code listing for that vintage of stock radios?

The radio works great, it's just this little issue and if it's not going to cause battery drain or wire heating problems, I have no problem with it working this way. It actually makes it easier to turn the radio on at night.

 

you'd need the wiring diagrams of the donor car. I have diagrams for various year 940's but none for 850's.