What does one make of these codes?

[Trae]

It has been more than two years since I pulled codes on the Renntech, but today The ASR light came on.
Tried several times to stop the engine, restart the engine, and drive around 50 miles.
Each time, the ASR light would remain OFF, but illuminate again after 12-20 miles.

Here are the codes I pulled today. Any ideas about the ASR light would be appreciated.
BTW, the cruise control works great and will hold any speed one wants all the way home.

Pin 6, code #21- ABS/ASR hydraulic unit, pressure switch (A7/3s1), charge
Pin 6, code #22- ABS/ASR hydraulic unit, pressure switch (A7/3s1), leakage


Pin 7, code #06- Starter lock-out/backup lamp switch (S16/1)


Funny that I have not illuminated an SRS light, because:


Pin 30, code #3- Driver airbag squib (R12/3)
Pin 30, code #5- Left front seat belt buckle switch (S68/3)
Pin 30, code #7- Front passenger airbag resistance
Pin 30, code #9- SRS malfunction indicator lamp (A1e15) or time limit for DTC readout /erasing exceeded

Don't know how old these codes are.

 

[Christian_K]

Get a new hydraulic ASR block. The pressure switches are not changeable... You can try it with a set of new relays that are located on the top of the block, but i think these codes mean a dead Hyraulic Block. Replacing it is rather easy, BTDT. You need star to actuate that pump on the new block to vent it (just like brake caliper venting). These units are available from 30$ to 800$ used on ebay. The more expensive ones are from the 500E/E420 ASR cars, the cheaper ones are ususally from other R129s or other models where i got mine from too, IIRC.

 

[Trae]

Looks like I had this same problem on my 93' back in 2012.
http://www.500eboard.com/forums/showthread.php?t=3123

Been so long, could not remember what I did.
Don't think I did anything as it disappeared on its own.

I think I may have a hydraulic ASR block from a 94' E420 with ASR in the barn that I rescued from the junk yard years ago. Will have to look for it.

 

[Christian_K]

Of course the S16/1 Switch is also a reason for it.
Maybe try to vent that installed ASR block first? Its not hard, you just need a star diagnosis....

 

[emerydc8]

Looks like I had this same problem on my 93' back in 2012.
http://www.500eboard.com/forums/showthread.php?t=3123

Been so long, could not remember what I did.
Don't think I did anything as it disappeared on its own.

I think I may have a hydraulic ASR block from a 94' E420 with ASR in the barn that I rescued from the junk yard years ago. Will have to look for it.

I vaguely remember that string, Trae. At the time, like you, I had a DTC 21 on pin 6 (ABS/ASR hydraulic unit, pressure switch (A7/3s1), charge), and I got tired of looking at it so I pulled the ASR light bulb out. I checked the codes a few days ago and now I have a DTC 24 (ASR charge pump) that cannot be cleared, so in my case I think I know what it is.

Since ASR is just a nuisance to me here in Arizona anyway, I may just let it go. I can imagine the ASR charge pump price is in line with the factory ETA prices. Unless I'm mistaken, I think that's the small electric pump under the master brake cylinder. [EDIT: I was mistaken. It looks like that's the pre-charge pump. The charge pump is behind the left headlight.]

Trae, in your 2012 post, didn't you fix the problem by bleeding the brakes?

 

[Efraim]

Hi,
inside ASR hydraulic unit there is pressure switch A7/3s1 which has two states:
1. open when the system is pressured, and ready to use.
2. closed when there are not enough pressure in the system. This is a signal for ASR control unit to power pressure and preload pumps until the pressure opens the switch.

If the switch jams to position 2) the pumps will be powered forever, until the system protection function will turn them off after a time period and switch on ASR light. I assume this can be easily checked by touching the ASR load pump (bottom part of ASR hydr unit) by hand and noticing simultaneous pump stop and light on.

If the switch is jammed to position 1) the control unit thoughts that there is enough pressure in the system and hence doesn’t power the pumps. No ASR light and no error codes. Opening the SP (bleeding plug) will show that there is not enough pressure in the system. In this case the ASR can reduce the engine output to stop wheel slipping but it can’t break the slipping wheel. This case is not easy to notice by driver if there is not different friction under left and right rear wheels.

The condition of A7/3s1 switch can be check by opening the electrical connector on top of ASR hyrd unit (under plastic cover). No special tools are needed, only multimeter, wiring chart, knowledge and time.

Althought the ASR hydr. unit is basically a part that doesn’t include any changeable components and Daimler & Bosch doesn't allowed to open it, it’s doable. I had issue couple years ago when the switch was jammed to open and managed to fix it even under the hood. I bought used ASR unit from wreck yard, took the switch and replaced to my car. I think I saved lot money since the list price for the whole unit was about 8k€.

Another reason behind missing pressure could be faulty pre pump and loose main pump.

 

[emerydc8]

Thanks. I think my switch must have been jammed in position 2 and the protective circuitry would turn the pumps off after about five minutes, concurrent with the ASR light illuminating. Over the years, the pump probably failed. I'll just pretend that I installed a permanent ASR delete switch.

 

[Trae]

Having a permanent ASR delete switch might come in handy. . . just be careful driving in all that rain you get in the desert.