'91 4matic, cannot erase codes; turn off light
 

--------------------------------------------------------------------------------

I finally had the transfer case in my '91 TE replaced with a used unit. Everything went well until it came time to erase the stored 4Matic codes to turn off the 4Matic light on the dash. I can't seem to read or erase the codes. When I ground pins 1 and 5 the 4Matic light gets brighter then dims when the pins are ungrounded.

After searching the forum I took a flyer and replaced the OVP just in case. One thread mentioned that over a periiod of time the 4matic ecm can lose memory and needs rebooted but I cannot find any info on rebooting the 4matic brain. Anyone one how to do this? Any other thoughts? Thank you.

I know you probably already did this...but my 4Matic light was on. Turns out the transmission fluid was too high. Then, I unplugged the battery for about an hour and it went off.

It occasionally comes on at acceleration from a stop though.

Thanks for the thought, tried disconnecting the battery and jumping pis 1 and 5. Anyone?

1 1/2 year later clarification...light stays on all the time now. System still seems to work.

:) Can I just unplug the light???

If you just unplug the bulb the system will fail the BIT. So, the system will not work, but at least you won't see the light. I fixed mine for a while with a piece of black electrical tape over the light. ;-)

Yup...I have electrical tape on mine as well. :/