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leongsoon

156 ABS pump running continuously

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Hi Smaky! Another week and another problem, this is really becoming a routine :(

 

My car's been fine for days since I reset the Selespeed error codes and got the shifter working again. All of a sudden today it displayed the array of EBD, ABS, VDC error with the Selespeed warning light and gear number flashing. I can only change gear within the first few seconds of the car starting. Any attempt to change gears will throw it back to N. The ABS pump doesn't stop even after I've shut the car down and pulled the key off.

 

I've tried removing and checking all relays in front of the battery as well as all fuses at the negative. Also tried removing two relays under the steering. ABS pump still wouldn't stop so I had to disconnect the BOSCH connector for now.

 

Battery and alternator seems to be fine as I've restarted it numerous times with no issue.

 

I still don't have a cable I can use to access the ABS and Airbag; it's on its way, but from FES I've so far gotten "P1752 Pump Relay" and "P1760 Brake Switch"

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The brake switch is the one I'd expect to cause this, basically, pop the switch out from the top of the barke pedal, Pull the plunger out, press the pedal down and refit the switch, clear the codes and see what happens.

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Thanks and another quick question Smaky! The KKL cable I'm gonna use to modify for ELM1 or KL1 isn't here yet, slooooow postage. I forgot in which module I did it; but I have managed to detect and clear P1760 Brake Switch yesterday with just a stock unmodified ELM327 interface. It's all fuzzy now but I might have successfully connected to the ABS module without KL1 / ELM1 after ignoring the prompt for the green adaptor from FES, either that or P1760 was detected within the Engine or Selespeed ECU modules.

 

Do you reckon I can clear the error code again this way after unplugging and reconnecting the brake switch to make it work? Or would I need to clear more error codes specifically in the ABS module?

 

Thank goodness for your advice; if not I would have had to limp the car to the workshop about 30km away in 2nd gear amidst town traffic, if it could even make it that far :)

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OK, so I got the brake switch out; it's not stuck at all, works smoothly, but I treated the connections to some contact cleaner just as well. My brake lights are working as they should be; no flickering when depressed, and brake lights light up when pedal pressed.

 

A scan gives me the same old; P1760 PUMP RELAY and P1752 BRAKE PEDAL SWITCH.

 

BRAKE PEDAL POSITION is alright; shows pressed when I step on it and off when I let go.

PUMP RELAY CONTROL is off with key at MAR and engine on. Is this normal?

VOLTAGE is 13.5 to 13.8

 

After clearing the error codes, I couldn't get them anymore in subsequent scans with engine on or key at MAR. I used contact cleaner on the ABS pump Bosch connector too, but it is still running non stop.

 

Is there anything else I left out and should go over?

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I think you may be needing a new ABS unit then, I suspect that one of the relays inside is stuck so either a good firm whack on the ABS unit will release the relay or you need to replace the whole thing.

 

But are you sure it's the ABS pump and not the Selespeed pump?

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It's the one attached to the firewall between the battery, correct? It's that pump which is making running noises and vibrating subtly. So far I've been disconnecting the Bosch connector with the pull up latch beside it to stop it. I tried whacking it with a stiff sandal but no joy, still runs. Wouldn't dare use any more force in case I break some hoses here and there.

 

Pretty positive it's not the Selespeed pump; had enough problem with Selespeed to know the sound well by now ;) I did remove the bumper on Saturday to remove the resonator box and tightened a bolt on the hose coming out of the pump. Could I have messed something there?

 

I do think it's a stuck relay too. I read one of your replies on AO stating there are 2 relays under a cover near the ABS pump but haven't been able to locate those; maybe I can check em if you'd point me to where there are. If it's really just a relay, can I just replace it instead of getting a new ABS unit altogether?

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Those relays are physically on the ABS brick, if it's running all the time then there will be a code logged in the ABS ECU, but this to me sounds like you are going to need an ABS 5.3 brick.

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Are the relays on the 5.3 accessible without removing the brick?

 

My 156 is a 2002 model with new interior, so I guess it's the Bosch 5.7 since that's what FES lists under ABS for "156 '02 Selespeed". To be honest I'm not quite sure what it is; the two aluminium heatsinks/relays are visible just beside the 12 coils once the ECU is removed. The label of it says 46745936 0265225031.

 

IMG_2515.jpg

IMG_2516.jpg

 

I've bought a 25A rectifier and uprated 75A N06 MOSFETs, can't trust my own soldering skills or lack thereof, so gonna have an electrician replace them for me later. I sure hope this is the culprit.

 

Btw, do I have to clear any error codes or run tests within the ABS module after refitting the pump? It was too tight in there to extract the ECU so I had to pull the whole pump out, the connector and solenoids have all been wrapped properly though! If it's necessary, how do I bleed the pump upon refitting?

 

Sorry for the long post and thanks once again :)

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The ABS ECU is back in with new relay parts! Doesn't run all the time anymore. Hooked up FES and got:

 

P0720 Transmission Gear Sys(12)

U1706 Engine > ABS data line

P0500 Vehicle Speed Signal

P1760 Brake Switch

P1752 Pump Relay

 

Cleared them off and they never appeared again. I think the first 3 errors appeared because I didn't snap the ECU connector on properly the first time.

 

With the key at MAR I can now engage all gears properly and the Selespeed warning lights have all disappeared, so that's some relief. I assume I'll still need to clear codes in the ABS module?

 

My brake pedal goes all the way to the floor now though. Do I need to bleed the ABS pump, or will just removing the wheels to bleed the front calipers do the trick?

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It's best to run the functions of the ABS unit but a normal bleed will normally be enough.

 

Nicely done with the relays.

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Upon hooking up FES to BOSCH 5.7 VDC for the first time I got and cleared the following:

P0000 Not Present

C1802 Battery Voltage Out Of Range

C1266 Pump Motor

C1460 Brake Fluid Pressure Sensor Faulty.

 

C1460 might be there because I left the reservoir cap open during the test. After clearing the codes the car can start and no error lights appear. The ABS/EBD error combo on Infocentre does come back whenever I try connecting to BOSCH 5.7 with FES, but there won't be any new error codes. FES was having a High Latency problem with my cable, and the ABS/VDC lights disappear whenever I disconnect from FES and the brake fluid was very low so I didn't think much of it. With the ABS/EDC error on the Selespeed hydraulic pressure will also drastically drop to 0 all of a sudden at times, but I don't know if that's related.

 

Today, after bleeding the brakes with the engine on, it seems the ABS ECU relays have stuck again and it's running non-stop once more. Brake bleeding did take very long; not sure if I was doing anything wrong but I had to bleed both front wheels at least 30 times each while the brakes were pumped repeatedly for about 20 minutes before the brakes were normal, haven't bled the rear brakes yet. Could it be possible that would have overloaded the ECU?

 

On hooking up FES I got "P1752 Brake Pedal Switch" and "P1760 Pump Relay" again as well as "C1266 Pump Motor". I can just redo the whole ECU relay thingy again, but am worried the relays will be fried again when I bleed the brakes. Btw, is P1760 the relay for the Selespeed or ABS pump? It has reappeared quite a few times and has finally started to get me worried.

 

I read that static electricity can damage the relays, so I reckon a check for potential gremlins that can damage the relays should be done, but I'm not very sure what relays or contact points I should look for. Sorry for boring you with all these Smaky.

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I didn't change it because it looks alright and seems to function with no fault, even the parameters are ok in FES, but I'll take your word and get a replacement later! Sure hope the workshop wouldn't want any of my fingers in exchange for the switch...

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The brake switch is the one I'd expect to cause this, basically, pop the switch out from the top of the barke pedal, Pull the plunger out, press the pedal down and refit the switch, clear the codes and see what happens.

 

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156BrakeSwitch.jpg

 

Finally got my new brake switch today. The one with the white plunger is new. Is the black one broken? The black one is originally from my car but I've never seen another one like it on ebay or anywhere else; I just see the white ones everywhere. I just noticed the difference in plunger length now. If the black one is stuck it definitely doesn't feel like it; parameters show fine and the travel is about same as the white one.

 

I'll just try fitting the white one now.

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Alright, turns out that the white plunger will snap inside and become short, fitted and tested no problem!

 

Phew, today's the first time I drove the 156 out in almost a month, it feels so good!

 

OK, anyway, I drove it for about 30kms and it behaved properly. Some brake warning did pop up on infocenter halfway but it was too brief; was gone before I managed to read it, I do think I glanced EBD and ABS again. Tested the car for a further 5 minutes and nothing else cropped up so I parked it and hooked FES up to get:

 

P1752 Pump Relay

C1802 Battery Voltage Out Of Range

 

I'm just relieved that the ABS pump is behaving normally now. Gonna let the car rest more until I sort the remaining problems, just to avoid frying the ECU relays again.

 

Is C1802 caused by P1752? May I know which relay is P1752 referring to so that I can put a new one in and hopefully fix the problem? Anything else I should check? Can't thank you enough Smaky!

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