Did you pull the fault codes?

Read the procedure here: http://www.eclassbenz.com/node/27

The site is for e-class cars but the procedure will be the same for your 98. Perform parts 1 & 2 then post your findings.

__________________
"It's not about how fast you can go, but how well you can go fast."

Bob in Richmond

'97 S320 (LWB), Ruby Red Metallic, 73k miles
'97 S420V, Smoke Silver Metallic, 155k miles