Lighting and Transmission issue

[sarb9184]

Hi there,

New to the forum and have recently bought a E24 635csi 1985 model, have got a very odd issue where the car drives fine with the headlihgts off but as soon as the headlights are turned on the gears seem to hold at high revs and do not change as normal, the gears also only go up to the 3rd gear and does not go beyond on that however as soon as the lights are turned off everything is fine and back to normal.

Since ive had the car have had the alternator changed to a brand new one as well as the battery which is working all fine, anyone know what i could check? Have also checked the earthing for the car but still no help.

Thanks in advance.

[wfwright2]

A possible issue could be the connections at the positive battery post. On my previously owned 87 635CSiA, one of the wires that fed the transmission controller has a loose connection (actually a loose screw) which realy played havoc with the engaging of 4th and general overall transmission behavior. After cleaning up and tightening the connectors all was well for the next 75000 miles when I "traded" it in for a wagon.
Electrical gremlins, especially intermittent ones are a pain and unfortunately common on these beasts.

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