You can build a homebrew code reader described in MENU#2. That will allow to read what the CFI module "thinks" is wrong. I would venture a guess that you may read DTC#10?

16 pin Diag Connector
Yellow: Read data from Pin 3
Power from Pin 16; Ground on Pin 1

DTC Readout Possible Cause of Failure
1 No fault found
2 Throttle position switch; wide-open throttle fault (WOT), signal faulty
3 Engine coolant temperature in CFI control module illogical
4 Air flow sensor position indicator potentiometer current illogical
5 Oxygen sensor signal illogical
6 Not used
7 TNA- signal (rpm) at CFI control module illogical
8 Altitude correction signal from ignition control module
9 Current to EHA is illogical
10 Throttle position switch; closed throttle position fault (idle)
11 Air injection system, open or short circuit
12 Absolute pressure values from ignition control module illogical
13 Intake air temperature illogical
14 Speed signal at CFI control module illogical
15 Not used
16 Exhaust gas recirculation switchover valve, open or short circuit
17 Oxygen sensor signal wire shorted to positive or ground
18 Current to idle control valve is illogical
19 Not used
20 Not used
21 Not used
22 Oxygen sensor heater voltage illogical
23 Short to positive in purge switchover valve circuit
24 Not used
25 Short circuit to positive in start valve circuit
26 Short circuit to positive in upshift delay solenoid valve circuit
27 Data exchange between CFI control module and ignition control module
28 Intermittent contact in engine coolant temperature sensor circuit
29 CFI and ignition control module reading different engine coolant temperature
30 Not used
31 Intermittent contact in engine coolant temperature sensor circuit
32 Not used
33 Not used
34 Engine coolant temperature read from ignition control module illogical

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Regards . . . . JimF
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'94 S500 Cpe

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