Heyoo, so new to the forum, not new to cars and a slightly new to me W124 E320 wagon. So down to the nitty gritty...SRS light is on with a code 1 which is no codes. I replaced the voltage regulator in the alternator cause it was tired, now its charging at 14v pretty solid. The light was off for 2 days after i changed it and the light came back on when i started it the other morning. Its on solid, no flickering or anything, its just on.

When I got the car i had pulled the passenger air bag to check the inter temp sensor blower motor, so i had cycled the key without the air bag in. Figured id have an SRS light, and well never saw one. Pulled the cluster and found no bulb (gee i wonder why) SO i pulled the low washer fluid bulb out and stuffed it in the SRS socket and the light was on. Cleared the faults and notta, the faults cleared but the light stayed on. So i did some research and put a voltage regulator in, first i pulled the old one to inspect it nad get the part number, pulled the brushes out a little and stuck it back on. light went off for 2 days. Got a new regulator (bosch) and put it on and same thing. Light was off for 2 days and came back on. the 10 pole connector under the passenger floor is clean and plugged in, this car has a clock spring, not the older type brush contacts.

What am i missing? All i can figure is the module is bad...the wiring diagram is dead simple, the bulb is tied to the 15r ckt in the ignition switch and is not fused, its connected to the power side of fuse 2, but doesn't go through the fuse. 15r powers fuse 1 and 2 and so far as i know i have no issues with the items on those circuits, cause the only other thing i could figure other than module failure is a bad ignition switch. It has an aftermarket radio in it, i pulled it out once and i dont think there were any odd things i saw in there in terms of grounds messed with.

What am i missing? This is driving me nuts and what is weird is when i did the regulator it was off for 2 days.

 

The whole vin and why? Sorry...that's something I don't just wanna post lol

 

Heck of a thing to say. It's got a 16 pin diagram box by the battery, it reads out a code 1. Which means no faults found. I can u plug other items and create codes...if I unplug the 10 pin red connector under the passanger floor for example, it sets code 3 and 4 for the drivers and passanger air bag squib. When I clear them I get a code one, indicating no faults found..yet the light remains.

Nothing is impossible, espically when it comes to this stuff...just a more odd problem.

 

It does not flicker it is on solid from the second the key is turned on its on solid. Every code list I have found for the w124 with the m104 engine says code one is no faults, 2 is a faulty control module, 3 drivers squib, 4 passenger squib, 5 left seat belt switch, 6 right seat belt switch, 7 front passenger air bag resistance, 8 voltage supply, 9 SRS light or time to clear dtc, 10 control module fault. What code list are you referring too? I will us burry the module soon enough to get the part number...but everything I have found indicates code 1 is no faults.

I'm going to pull the cluster again to check the bulbs, it occurred to me today there is a possibility they are not in the correct holes. I only pulled the cluster to check the SRS light when this disaster started and put a bulb in it, I didn't check to see if it was in the correct hole haha.

 

Thank you Plutoe for making me stop and think for a second haha.

It hit me like a ton of bricks when i rolled over in bed last night, for what ever reason. There is an EGR code i knew about, figured ill get to it. Well i just cleared that code and the SRS light turned off.

Someone went to smog the car and the check light was on, so they pulled the bulb out and stuck it in the SRS hole, then took the SRS bulb and put it in the check engine light hole. So you get a bulb test indication and the light would go off when the car started. This will look legit so it will pass smog, as its required for California smog check to light up and go out when the car is started. Last night i pulled the 10 pin red connector and saw the check engine light come on, i thought wtf, that makes no sense...but since it was at the end of my day and i was exhausted it didnt register the bulbs were mixed up. So this was a brain fart on my account. the missing bulb was so it didnt look like the SRS light was on. So yeah, mixed up bulbs. Done and done, thanks for the help!