New modulator,what the hell is happening

jorjio_k · Oct 3, 2011

hello gents;
today i have replaced the modulator with a used one from a breaker,wow what a difference in braking,untill the abs kicked in for the first time,and wouldn't release leaving the car with a screetching halt and the three amigos displaying then relasing again.
checked for faults and nothing is there,then again while parking it on gravel the rear tire span and traction control kicked in then the car stops to a screetching stop.
brakes are great untill the abs is used in braking or traction control,then they wont release untill the abs pump stops its work.
is it a duff modulator or something else is wrong?didn't have this problem before replacement!!

rasheed · Oct 3, 2011

have you checked that you got the right one for your model year?

jorjio_k · Oct 4, 2011

Honestly i didn't and i don't know how to check for the part number but the braker knew which model i am talking about so he is the one who choose it,could it be he gave me the one of the 4tc control system?or maybe the pipes are installed wrongly in it?all i know that it was so damn scary to drive it and today it is going back again to the garage,what a waste of time and brake fluid.

rasheed · Oct 5, 2011

Yes although I don't know what would happen if you put the 4 wheel TCS on a 2 wheel car. Either it would effectively upgrade you to 4 wheel TC but you might also need an ABS ECU upgrade for that, or, if its sending both front and rear pulses to just the rear wheels and these pulses overlap then possibly the rear brakes would just lock. To be honest I've never come across this problem of locking up on ABS. I would have guessed either ABS ECU or modulator and in your case since we know this started when you changed the modulator that has to be the place to start.

As for part nos its easy enough to find the correct part no for a '95 on the web or through Microcat but I think what you mean is that its not stamped on the modulator so you can't tell which you have.

Tell you what, if you have access to diagnostics, see if there are any clues in the fault codes. Secondly, bleed, bleed, bleed, both at master and at each corner. If these don't work and since you're spending time and fluid already, take it out and physically compare both modulators for any differences in housing design, pipes, connectors etc. Maybe even try using the old one again and see if the behaviour comes back to normal.

Ultimately you have two options. If the replacement is the right model but its not working, give it back. If the replacement is for a later model with 4 wheel TC then ask your breaker to lend you the ABS ECU from the donor car and see if this now makes a difference. You might need to contact someone like Irishrover or Rick the Pick first to ask if the BECM will allow the changes.

Good luck!

kooky_guy · Oct 5, 2011

I remember that someone was looking at upgrading a 2 wheel TC to 4 wheel TC before, but the conclusion was that it wasn't easily doable. The ECU connectors are completely different for a start, apparently.

rasheed said:
Yes although I don't know what would happen if you put the 4 wheel TCS on a 2 wheel car. Either it would effectively upgrade you to 4 wheel TC but you might also need an ABS ECU upgrade for that, or, if its sending both front and rear pulses to just the rear wheels and these pulses overlap then possibly the rear brakes would just lock. To be honest I've never come across this problem of locking up on ABS. I would have guessed either ABS ECU or modulator and in your case since we know this started when you changed the modulator that has to be the place to start.

As for part nos its easy enough to find the correct part no for a '95 on the web or through Microcat but I think what you mean is that its not stamped on the modulator so you can't tell which you have.

Tell you what, if you have access to diagnostics, see if there are any clues in the fault codes. Secondly, bleed, bleed, bleed, both at master and at each corner. If these don't work and since you're spending time and fluid already, take it out and physically compare both modulators for any differences in housing design, pipes, connectors etc. Maybe even try using the old one again and see if the behaviour comes back to normal.

Ultimately you have two options. If the replacement is the right model but its not working, give it back. If the replacement is for a later model with 4 wheel TC then ask your breaker to lend you the ABS ECU from the donor car and see if this now makes a difference. You might need to contact someone like Irishrover or Rick the Pick first to ask if the BECM will allow the changes.

Good luck!

jorjio_k · Oct 5, 2011

thank you rasheed for your lovely reply;
after spending onother tiring long day at the garage,we removed this modulator and replaced it with onother one,problem solved,ended up paying 50$ for brake fluid although we tried to save some of it but hey no pain no glory,man bleeding is a pain in the a$$,brake fluid everywhere in the engine compartment,but now i am happy at least and satisfied,i don't know how i was driving it before with my old duff modulator,never thought that the brakes pedal on the p38 is so smooth when it is working properly,so after an entire year of driving it with a click in the brakes pedal and sometimes no brakes now i am very pleased.payed 300$ in total labor and modulator and fluid as well as an air filter.i still can't believe that a new modulator costs 700$ where i live.
i don't want to cause myself a headache and trying to figure out what was wrong with earlier modulator,i believe it is either the duff solenoid inside of it or a broken axle inside of it,anyway i gave it back to the braker and got the other one.
thank you gents
cheers

jorjio_k · Oct 5, 2011

i forgot to mention the reaction of both the braker and the mechanic when i explained the differences in the 2 tc an 4 tc,they stared at me with their mouth open and looked at me like i am a complete idiot,and said all modulators are the same (yeah right),so hat down for landyzone,for sure i made both of them think.
applause for LZ you rule

rasheed · Oct 5, 2011

lol! at some point or another all p38 owners end up becoming mechanics whether they like it or not! :doh:

glad you solved the problem.

New modulator,what the hell is happening

jorjio_k

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rasheed

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jorjio_k

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rasheed

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kooky_guy

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jorjio_k

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jorjio_k

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rasheed

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