View Full Version : ABS/Traction control question

01-30-2013, 12:37 AM
On the road to restoring my van to full working order I have gone out on a limb and bought a second hand ABS pump (module built in).

I plugged it into the harness (and connected the ground) tonight and read the codes, the good news is they are totally different to what I was getting on my existing pump, and even better I was able to clear the ABD light on my dash. The not quite so good news is that the part number still appears garbled although the codes are now all coherent, and the reason for the thread, I am left with an error code:

C1303 Right front axle solenoid valve (release):
open circuit/short circuit
-> verify the internal resistance of the solenoid valve
- while IGNITION = OFF : 2.8 - 6.6 Ohm
-> Verify also the wiring and the Hydraulic unit and the traction system

Presumably this refers to the solenoid within the ABS controller - how do I test it, through the ECM connector pins?
If the solenoid is at fault, is this something that can be repaired, and is it a feasible DIY repair or do I need to send it away?

I am trying to decide whether to keep the pump or make a fuss to the seller about it having a fault - there was always a risk, when I asked if it had been tested I was told it was taken from a working vehicle. I suspect they didn't think to test the ABS before breaking it, probably drove around with it not working for years without even knowing if it doesn't put the dash light on!

The trouble is pumps with matching part numbers for mine are getting pretty rare, this is the first one I have seen in several months so I am erring towards keeping it and sending one or other away for testing and repair.

Eric Experience
01-30-2013, 10:31 AM
Tricky question. I would pull the known bad one apart to determine if the coil appears at the plug. I suspect it does so the ECU can monitor it. Eric.

01-30-2013, 11:11 AM
Haynes book does give procedure for separating ecu from hydraulic unit (and tightening order to refit it) so I think I'll go with your suggestion, if it looks like it will come apart easily - maybe just corrosion on internal contacts or something.

I have heard mixed things about getting these repaired, but some of the outfits have some impressive videos. I think my plan is to have a look at the worst one and see if checking the solenoid looks feasible/safe (from the perspective of making a doorstop out of the unit), and then send it away to see if its ecu can be repaired - if it can I'll keep the other as a spare.

Hang on, 2 identical part number pumps, one with bad ECU the other with possible bad hydraulic unit, am I missing possibility 3? - marry the good ecu to the possibly good hydraulic unit.....

I think I can do something!

Cheers Eric, I might not have thought of pulling one (or both apart), it looked a bit daunting (the bit about "do not damage the seal, it is critical to the unit" probably scared me).


01-30-2013, 11:50 PM
Anyone know roughly how much brake fluid the complete system holds?
LWB T1N with ABS and ABD.

Aqua Puttana
01-31-2013, 12:43 PM
Anyone know roughly how much brake fluid the complete system holds?
LWB T1N with ABS and ABD.
Why do you ask? Is it just to buy enough fluid for a fill?

A complete flush is said to take 2 bottles (I presume quarts?). There's quite a bit of extra used for a flush so you shouldn't need more than that.



01-31-2013, 04:49 PM
Basically yes.
It is recommended to drain before working on the pump plumbing (makes sense, no hoses to clamp) so it will require a full bleeding session after that which is going to be at least equivalent to flushing, plus using an ezibleed you need about a litre (quart?) extra for the bleeder reservoir.
They say never to put old back brake fluid back in, which I dont, however once I am confident I only have new fluid coming through I may return some of it if I am going to run out. I think I should get 3l to give myself the best chance.
Febi list a 5l bottle but I can only find 1l bottles

Good thread link - Carl says 2-2.5 bar for the MB flushing machine, I think I normally use about half that (20 PSI) with ezibleed so might look into upping the pressure a bit - it depends on the seal of the plastic bottle cap!

Some scary prices in that thread for having it done, I know I have bought a computer and software but the dealer already has that and I have found the fluid for 8 per bottle (plus postage, MB won't post out but others will) which makes the prices seem, well, scary. I just hope carsoft actually does activate the ABS pump when I ask it to (have seen it on the menu!).

Eric Experience
02-02-2013, 09:49 AM
Don't get to stressed about activating the pump. that is for people stuck in a workshop. You can clear any air from the pump by driving to a quite road and locking up you wheels several times to allow the abs pump to do its thing. Eric.

Aqua Puttana
02-02-2013, 10:43 PM
The brake pump system may not be as static as many people think. I know the NAFTA Sprinters have BAS Brake Assist System. That system also uses the pump pressure and valve system to enhance braking. It isn't just the ABS being employed that causes the system to circulate your brake fluid.

"The pressurized brake fluid is stored at about. 180 bar (2600 psi!) in a reservoir known as the accumulator. From the accumulator the high pressure brake fluid is supplied to the hydraulic operating cylinder in the master cylinder assembly. Commands to utilize the pressurized fluid comes from either 4ETS or BAS. When the brakes are applied and BAS deems it necessary, a lever connected to the brake pedal releases varying amounts of the high pressure fluid to assist in stopping the car."

In the winter I do go to snow covered parking lots and skid around. It's fun, but it also gives the ABS system a workout. Similar to what Eric suggests in the dirt and gravel.

Since flushing my system I have been sucking out the brake fluid reservoir and refilling it with fresh fluid every Spring and Fall. I figure that should help to keep the moisture level down. Moisture will basically equalize when there is fluid contact within a system. I figure suck/fill on the T1N system is easy and cheap. It certainly can't hurt. Do with this information what you will. vic