ABs module and shifting

[99sho-time]

how much does the ABS module have to do with the transmission? I have 4 new wheel speed sensor and the bas light still goes off and the ABS light seems to go off the most in the rain.

 

[E1]

ABS 'IS' your speed sensor. Without it, car has no idea what is going on speed wise.

Dead ABS = all kinds of things get weird.

 

[99sho-time]

Yah I noticed sometimes when I'm decelerating the RPM's will freaking DIVE and I mean dive down it will recover but. I noticed it has nothing to do with me pressing the brakes either. I got the tranny rebuilt but they couldn't figure why the first shift is so hard it's a shop I trust so I dunno.

sometimes I do kinda feel some sensation of brakes going off lightly when I dont press them.

How do i tell what to do? like if its the pump or the module or wiring?

 

[stephen newberg]

If it is the pump there will be no effect on your speedometer and the only feel difference is the peddle to me seems a touch mushier, but the breaks on the Gen III were never what one could call aggressive. If its the module I suspect (but do not know for certain) that it will mess with the speedometer. Wiring could go either way, depending one where it is at fault.

pax, smn

 

[99sho-time]

Hey guys slight update i finallyw as able to catch the ABS light on the scanner and its a c1175

 

[stephen newberg]

C1175 Speed Wheel Sensor LR Input Circuit Failure

pax, smn

 

[99sho-time]

it has all 4 new wheel speed sensor. just not sure what to do or how to tell if module is bad.

 

[Devin]

Disconnected harness? Is something rubbing on the harness?

 

[99sho-time]

At first i noticed it was sorta loose so I took ti out cleaned it with contact cleaner and i sued dielectric grease. I noticed it was sorta dirty with a decent amount of sand grits in it. the car shifted alot better but not perfect. the next time i drove it the abs light comes back on and it started shifting real hard again

 

[GEN 3 SHO FAN]

It may be also the toothed wheel. If some tooth are gone, this can send false infos to ABS. Rear toothed wheels aren't made with the same metal as the front ones which are more reliable. The rear ones are subject to rust and can loose all their teeth. However, it's very easy to check and you probably made a check up for that. (?)

 

[99sho-time]

that left rear ring the exciter ring is rusty but people were telling me that one shouldn't effect shifting that the front right is the one that's important which is in fine shape.

 

[GEN 3 SHO FAN]

Strangely, it's the same wheel (LR)...

The people whose telling you about ABS module were "ordinary" mechanics or SHO owners with the specific knowledge ? All I read here and elsewhere, say that all four wheels infos were computed by the SHO to make decisions. The ABS on s SHO seems a lot more important than a SLO or a today normal car. At least, the ABS module itself seems to broke rarely (and it's a good thing $$$). I will bet on a wheel (they eat more salt than the module) and yours sensors are news, the remain faulty parts is the exciter, probably LR. Moreover, you felt a amelioration when you cleaned these parts...

At least, I will start with an inspection of the ABS module as some had good results in the past in cleaning / replacing ABS module. Maybe cleaning connections of the ABS module after 18 years will do the job. I must admit that the connection of my ABS relay (SAI pump relay) which is just a little lower of that had connector completely corroded and disappearred...

http://www.v8sho.com/SHO/ABS Exciter Ring Grooved.htm

http://www.v8sho.com/SHO/ABSSpeedometeCruise.htm

 

[99sho-time]

Okay so i changed the hub out and nothing seems to have changed. I guess im gonna try and replace the module.

Anybody know what the process is like getting the module out what kinda of screws those are?

 

[E1]

It sucks. They are Torx, IIRC. I may have a whole ABS module around here somewhere...

 

[stephen newberg]

I do not suppose you have a working ABS pump for the SHO sitting about Eric? If so, I would take it off your hands.

pax, smn

 

[E1]

I do not suppose you have a working ABS pump for the SHO sitting about Eric? If so, I would take it off your hands.

pax, smn

Let me do a little garage tunneling tonight and see what turns up.

 

[stephen newberg]

Thanks Eric.

pax, smn

 

[99sho-time]

Hey not to drag this out more but now it was a c1165 and I put a new one in cleared it and keeps coming back.

And I have to ask are we absolutely sure that if an abs light is on it will effect shifting?

 

[sperold]

In the old days there were no wiring connections between the engine and the transmission. The transmission got signals from the intake manifold vacuum and ran it to a modulator that governed the shifting; and a mechanical linkage connected your throttle to the tranny to dictate down shifting to the so called passing gear.
Your car needs to know the same information but does it with a computer and the wiring to the transmission.

Your computer needs the engine RPM and ground speed. The ground speed information is supplied by the ABS.

There could be a case where the ABS system light is on and it could still provide information to the computer (ie the speedometer is still registering), but that is beyond my ability to comment on.

 

[stephen newberg]

Yes, the pump for the ABS can die, which will give you a light, but otherwise data still flows just fine and actually everything works normally except you have no ABS. That is, you have a mechanical fail but no electronic one.

pax, smn