New Voltage Regulator still have SRS light on - PeachParts Mercedes-Benz Forum

sptt · #1 09-20-2009, 10:18 PM

OK...I replaced the way worn down voltage regulator on my 91 300E alternator (I don't think it was ever replaced! One brush was half as short as the other brush and worn down past the little emblem on it). So far the idle while in drive has been perfect where it was a little rough (from one of my earlier posts) so I hope that stays now. However, the SRS light has been coming on and off way more now since I replaced it (before...a couple times per drive). I'm still waiting on a new OVP and hope that will fix it but if not, what do I need to check on next. I did read that there are some contacts behind the sterring wheel that I can spray with some contact cleaner but it does not happen when I'm turning, only driving straight down the highway with just myself in the vehicle. It comes on for a few seconds then turns off. Sometimes a little longer, sometimes a little less.

ps2cho · #2 09-20-2009, 10:34 PM

Yep. I have the same deal on my wagon. I personally live with it and it only happens on the freeway when I have been driving 50+ miles...so it hardly ever happens for me. It is definitely a connection behind the wheel.

sptt · #3 09-21-2009, 12:01 PM

I'll try to spray some of that contact cleaner up and in there. Otherwise, a piece of black electrical tape may solve the problem by covering the light but do not want to have an actual safety issue with the SRS without resolving. Thanks for the confirmation. When you see that red light pop up, it gives you a slight concern at first

lkchris · #4 09-21-2009, 12:31 PM

MOST often, SRS light on a W124 is fixed by new contacts in steering wheel.

The relationship between SRS system and OVP relay is ZERO.

ps2cho · #5 09-21-2009, 12:58 PM

If it bugs you that much, you can always remove the bulb, although I don't recommend it.

workerunit · #6 09-21-2009, 01:06 PM

I had a similar problem on my 190E. The SRS light would come on intermittantly while driving straight ahead, wiggle the steering wheel and the light would go out. I had to pull my steering wheel to access my Ignition switch so I examined the horn and SRS contacts. The copper contact rings in the steering wheel were worn concave and the brushes were also worn. there was a large amount of black dust material around the contacts. I cleaned the contact rings with electrical contact cleaner [DeOxit]and a pencil eraser and also cleaned the contact brushed for the horn and SRS system. I used compressed air to remove all the dust material and reassembled. so far so good the only time I see the SRS light is on prove out and my horn also seems to be louder.

FYI, My steering wheel bolt was on extremely tight from the factory, a 1/2 inch air gun would not remove it until I took a small torch [real small] and heated the bolt thoughly, then the bolt could be remove with the impact gun. M/B used red locktite on the steering wheel bolt. I used a very small amount of blue loctite on the cleaned bolt during reassembly.

glenmore · #7 09-21-2009, 01:18 PM

There are two brushes under the steering wheel much like the brushes in the voltage regulator. These are seperate little spring loaded brushes and are pretty cheap. But they look like they would last quite awhile so not likely to the source of your SRS light. My SRS fault turned out to be the horn hub that the brushes rub against. This is a bit more expensive, about $100 nowadays. So you might check the brushes and clean it out before spinging for the hub. There was nothing obvious about my hub being defective, it looked fine. But changing it out eliminated my SRS light. Also SRS lights may be from your seatbelt connections.

If you notice a correlation between the turning of the steering wheel and the flashing of the SRS light, then could be brushes but most likely the hub.

Another person and a long cheater bar come in handy when you try and break the steering wheel nut.

glenmore
1991 300CE
2000 C280

sptt · #8 09-21-2009, 10:53 PM

WOW! Thanks for all the replies guys! Is there a procedure for getting the steering wheel off with the air bag on it to gain access to the fort knox bolt holding it in? Since it doesn't happen when I steer or turn the wheel, it must be the horn hub brush I imagine. Should I try the contact cleaner spray in the small access behind the wheel first? Will it screw anything up? Today I spun all of the fuses in the fuse box and my passenger side window came back to life! Go figure (I learned that from another thread). Again, appreciate the responses and all of your help!!!

Steve

ps2cho · #9 09-21-2009, 11:47 PM

Quote:

Originally Posted by sptt

WOW! Thanks for all the replies guys! Is there a procedure for getting the steering wheel off with the air bag on it to gain access to the fort knox bolt holding it in? Since it doesn't happen when I steer or turn the wheel, it must be the horn hub brush I imagine. Should I try the contact cleaner spray in the small access behind the wheel first? Will it screw anything up? Today I spun all of the fuses in the fuse box and my passenger side window came back to life! Go figure (I learned that from another thread). Again, appreciate the responses and all of your help!!!

Steve

I would recommend you go buy like 20 of each kind and replace them all. I bet that window won't last long. They are like $0.20/each

workerunit · #10 09-22-2009, 02:42 AM

I can tell you that on a 1990 190E the steering wheel air bag comes right out with a small torx driver [I do not remember the size] disconnect the battery first however. There is a small connector attaching the airbag to the hub. the steering wheel is held on with a large torx fasterner[ I do not remember the size] Once the fastener is loose the steering wheel pulls right off the splined hub.use a small punch or sharpie pin to mark the steering wheel and steering column shaft so the you can put the wheel back on straight. The hardest part of the job for my car was the steering wheel bolt, it was on way, way tight. use a little bit of heat on it to soften the loctite.

glenmore · #11 09-22-2009, 12:28 PM

There are 2 captive torx bolts on the back of the air bag. They are recessed so make sure you have the right tool to avoid stripping them. Unplug battery and wait awhile to let all charges dissipate. Have a small screwdriver handy to pry off the small red plug.

glenmore
1991 300CE
2000 C280

sptt · #12 09-24-2009, 09:04 PM

Just to let you know...after I spun the fuses in the fuse box earlier in the week, I have had many things start working that weren't including..sunroof, passenger side window, and SRS light has yet to come back on (hope it stays that way!). I still have a slightly rough idle after engine warms up to 80 c so I'm going to replace the Distributor Cap and Rotor. Next will be the vacuum lines. I'm noticing some of the rubber connectors that go to the manifold are brittle and heat worn. Is there any particular one that would affect idle while in drive at a stop that I should hit first?

Cal Learner · #13 09-25-2009, 07:28 AM

Quote:

Originally Posted by sptt

Next will be the vacuum lines. I'm noticing some of the rubber connectors that go to the manifold are brittle and heat worn. Is there any particular one that would affect idle while in drive at a stop that I should hit first?

Any vac leak will likely affect idle quality, but if you're looking for a place to get started, try the two rubber hoses connected to the idle control valve.

sptt · #14 09-26-2009, 07:23 PM

Just want to let you know since I spun the fuses in the Fuse Box, I still haven't had the Passenger Side window stick and SRS light has not yet come on again. Will post back if any changes. Still working on trying to pinpoint the warm idle problem...vacuum line seem OK but that is only with the Car Cleaner spraying Test. Thanks!