ABS Problems (Phase 1 2wd 1988)

[renault5gtt]

Pleez, does anybody have Idea what?s wrong now?

I must get my R21 inspected soon, and I?m out of ideas
Last time I sorted it out myself.... it was the presostat.

but
The orange light it lit and stays on. After selftest the handbreak light goes off but not the other one.

I have tried another ABS ecu, no luck.

I have checked all the sensor rings (those are little bit corroded but every tooth is there)
I measured the resistance from the wheel sensors (ecu harness)
and the ohm values was bout 1K each (1020-1040)
I measured the voltages from sensors (Driving bout 40 km/h)

FR = 0.7
FL = 1.1
RR = 0.6
RL = 1.0

Does anybody know what is maximum difference in voltages?
Is those values right ??

I know that the clues are right there, but cannot see them

Cheer?s

Sam (Member number 140)

 

[Smallboy]

as explained in another post, i need Lyndon to confirm your membership as you are not on the members database so i can alow you access to post to the problems forum.

i will move this topic to problems.

 

[DaveL485]

Sensors and targets.

Is it a Quadra?

Also when you start the car does the light go out then come back on after you have started driving or is it on all the time?

 

[renault5gtt]

Nope Dave,

It isn?t Quadra
It would be quite easy to read those fault codes or blinks
Cannot do that 2wd models. Even XR25 won?t able to read those, by?????h

Do you have any ideas? Or knowlegde ex. how much difference is allowed
in those wheel sensors ? (voltage etc..)

One possibility is that I?m going to strip the hole ABS system away,
or trying to figure way to cheat in inspection

Greets from Finland
?Sam

 

[DaveL485]

when you start the car does the light go out then come back on after you have started driving or is it on all the time?

 

[renault5gtt]

Joup,

The Light is on all the time, only the handbreak light turns off.

Could it be relay problem (in the engine bay??) The fuse?s are OK, thou.
There?s couble of nasty ones (with the diodes) I think..

" ABS wizz must be rocket scientist, (Electrics, hydraulics and mechanics) "

?Sam

 

[DaveL485]

Hmmm

If your light is on all the time I'd say it was a sensor fault.

Test the resistance in Ohms of the sensors with the car stationary. Mine come up at 1.10-1.20 give or take and its fully operational.

 

[graham]

with abs you are right on testing for the voltage all the voltages should be the same i am looking into the tolerance values but i know it is not alot. did you take all your reading dead stright?

 

[renault5gtt]

Jep,

I measured the voltages and those values are quite right.
I?m afraid that the tolerance is not that much too ..
Ohms was bout 1K all, I know that the circuit is not broken..

FR = 0.7
FL = 1.1
RR = 0.6
RL = 1.0

I would like to know that, what is the voltage in the new sensor ?
I mean if it is like 1.8 volts, then even I change example FR sensor to
new one, the voltage difference will be there again.. not nice

This is quite diffucult...

Like I allready said, electronics, mechanics, hydraulics all together is too much.

ps. How many times you are able to push brake pedal before your
pump starts to pressurise again ?? Mine is bout three times..
I think I must order the new accumulator (the ugly ball) also?
Or is it fixable.. ?

Greets al ay...

First snow came

 

[DaveL485]

Hmmmm.

Try changing the computer unit. If not get a spare sensor and plug it into the 4 different inputs for the car sensors one after the other, turning the ignition on each time to see if the light goes out after about 5-10 seconds.

 

[graham]

know it sounds mad but do you have acess to i 2 or 4 channel osillerscope

 

[DaveL485]

* Ocilliscope *

 

[renault5gtt]

Re: Hmmmm.

Try changing the computer unit. If not get a spare sensor and plug it into the 4 different inputs for the car sensors one after the other, turning the ignition on each time to see if the light goes out after about 5-10 seconds.

The ABS ecu thing I have changed (Tryed from working one...) and
mine worked in other thou..so that?s not the prob.

But the switching sensors thing was too easy even think about..
That I haven?t tryed yet.. I have couple of spare ones, working ones
I hope.. (One front, and one back)

I must try that today after work...
As I allready said "all the clues are there, I can?t just see them"

D?nx Dave

 

[renault5gtt]

know it sounds mad but do you have acess to i 2 or 4 channel osillerscope

Yep Graham, I have old Philips Oscilloscope in work and studyed it little bit.

When I measured the Ohm?s, and voltages, and those were "right"
so next thing was the waveform test, and it looked allright either..
It was same kind in all wheel, and what faster you drove that tighter was the waveform....

Even those sensors looks fine (all the test?s), I think that the "gremlin" is somewhere there..
I try to swap today those spare sensors of mine, and see what happens.

Have you got the voltage tolerance allready ??
Even Dialogy?s won?t tell anything... or Autodata

?Sam