'89 C4: Front Differential Interlock Problems??
 

My '89 C4 has 42500 miles on it. Today, on my way to work I had trouble after about 20 minutes of highway driving. It started to surge, hesitate, and buck - the alarm panel kept lighting up with the central alarm (!), ABS warning and the interlock indicators. After a minute or so (after slowing down and checking it out), the car settled down again. It felt like the front diff was grabbing and releasing in a pulse-like, jerky manner, and I thought I could hear the sound of solenoids engaging and disengaging. I don't know if it is related, but my radio wouldn't stay on during this time, either... Any known or easy fixes or do I need to go straight to the mechanic? Thanks.

Sounds electrical. Maybe a bad battery or most likely a, failing alternator/ voltage regulator. do a search here for old threads.

Hi,
I also had the same kind of problems.
I can confirm that after changing the battery everything was ok ;)

Luc.