Folks,

A few posts recently has gotten me to wonder about this issue.

In my vehicle (94 E420) I can read codes that are stored in my vehicle. I assume that codes are stored whenever the Check Engine light is on.. and no code when it is off.

According to JimF's site (https://www.k6jrf.com/MB_S500.html),

there are many modules that send out codes (all have different sets):

Distributor Ignition Module [DI] DTCs
Diagnostic Module [DM] DTCs
Hot Wire, Sequential Fuel Injection Module [LH-SFI] DTCs
Base Module [BM] DTCs
Electronic Accelerator/Cruise Cntrl/Idle Speed Cntrl Module [EA/CC/ISC] DTCs
Anti-lock Brake System w/ Acceleration Slip Regulation Control Module [ABS/ASR] DTCs
Supplemental Restraint System [SRS] DTCs
Anti-Theft Alarm System [ATA] DTCs
Convenience Features [CF] DTCs

My assumption is that the little push button and LED in my engine compartment (I think it's called X/11) only reports out codes from the Diagnostic Module. Is this correct?

This car is not ODBII compatible as it is a pre 96 vehicle. Without spending $$$ on an elaborate reader, is there a way to check for codes in other modules?

I have read posts about a Craftsman Digital Volt Meter that can be used to read codes and other data from the vehicle. Can someone elaborate?

__________________
Willy

'94 E420 White

Mods
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Berg Werks Keyless Entry
Buzzer replaced with Chime
Dash Light Upgrade
Burlwood/Leather shift knob
Alpine CDA-9815 Head Unit
2002/2003 16" C Class 7-Spoke Wheels
Updated "Chip" to fix Code 19 problem