Under the hood there is a cover near the firewall on the passenger side. The diagnostic port is in this cover. Under this cover there is a module box, you want to remove its cover as well. Inside there should be a module that has 4 red 10A fuses in its top. Check those fuses, likely one is blown.

FWIW, I usually look for posts with 0 replies to try to help out on tough problems, but rarely visit the SL sub-section..

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90 300TE 4-M
Turbo 103, T3/T04E 50 trim
T04B cover .60 AR
Stage 3 turbine .63 AR
A2W I/C, 40 LB/HR
MS2E, 60-2 Direct Coil Control
3" Exh, AEM W/B O2
Underdrive Alt. and P/S Pulleys,
Vented Rear Discs, .034 Booster.
3.07 diffs 1st Gear Start

90 300CE 104.980
Milled & ported head, 10.3:1 compression
197° intake cam w/20° advancer
Tuned CIS ECU
4° ignition advance
PCS TCM2000, built 722.6
600W networked suction fan
Sportline sway bars
V8 rear subframe, Quaife ATB 3.06 diff