rltc wheelspeedsensor

[arnout]

Hi guys,

Today I installed a RLTC unit in a mkIV supra. The car runs great and the monitor program gives the correct wheelspeeds on all four wheels until 80 km/h (55 mph). Until then everything is fine.

After about 80 km/h I get el weirdo fluctuations in the speed signals from the rear speed sensors only. The front speed sensors continue to work correctly but the rear wheelspeed sensors give readings from anywhere between the 'correct' wheelspeed and about double that.

If I accelerate from zero to say 120km/h all goes well but the car

starts to misfire from 80km/h because the RLTC things it looses

traction (sometimes).

What is this problem? Are the wheelspeed sensors dirty or something?

Should I try another RLTC unit?

I soldered the connection on the ABS ECU and everything is wired up correctly. I used the ABS+ signals on all four wheel speed sensors.

 

regards

Arnout

http://www.supras.nl

[matt]

That does seem like the signal is getting corrupted.

 

I trust you have the correct tyre sizes in the config and the right way round?

 

The wheel sensors have 41 or 42(from memory) teeth if that helps? Best to search on here for the correct figure..

[arnout]

The wheelspeed is correct until 80 km/h. Above this speed the signal gets distorted.

[matt]

Yeah, sorry was scanning

 

Its not something I've heard of .....

might try pm'ing Phil (Terminator)....... he's helped a lot of people with RLTC , maybe its something he's seen before

 

I think you've pretty much covered it ........ try cleaning the sensor/pickup or try another unit.

[matt]

Just a thought..........

 

I recall there was some discussion on wether or not to earth the sheilding on the RL ABS loom.

 

Did you earth the shielding?

[arnout]

No I did not. That might be it yes. I thought it was shielded on the side of the RLTC unit. If it's grounded there and I also ground it at the ABS ECU then you would have a grounding loop I thought. I can try to ground it at the ABS ECU also.

[THOR Racing]

Transmission of a signal shielded by a ground sheith works better when only ONE side is grounded.

 

Otherwise you get ground loops (current loops) and more interference than without the shield.

 

I'd recommend only grounding at one end.

For ANY signal.

 

It's odd the signal dissappears above 80km/h as poor ABS sensors usually have poor signal amplitude at low RPM which increases as rpm increases (i.e. road speed)

 

Try swapping the rear sensors with the front (on the RLTC loom) and reconfigure the unit with the software.

 

See if the bad sensors move with the wiring change or if the fronts now appear wrong which would suggest an install problem.

 

Pete

[Terminator]

What software are you using?

 

The older RL software did throw up some strange behaviour.

 

I have helped over 50 people with RLTC files in three years I think two units were faulty.

 

Are you taking anything else of the speed signal wire?

 

Both rear wheels sensor dropping out at the same time due to faults is very unlikely

 

These symptoms can be the result of a failed configuration run may be worth trying that again.

 

I have never seen a dat or another file sold as a MKIV file that was set up correctly.

 

I can send you a data and Graham Rudd’s software, there are no reported issues with this tried and test software/dat combination.

 

ABS pulse count is 48 BTW