Mark Vii Choice Exit Limit switch question

[gomerpyle]

New error code for me. GAH-S3 F020 Limit Switch input Exit Travel Limit.

I have had a good run of no errors but now this one has come up. happens about every other car so can't really leave the wash open.

Maybe unrelated but during one cycle. The power washers went on and off several time at the front of the car before they fully engaged. I could hear the pump turning on and off in the equipment room.

Any ideas on what to look for.

 

[chaz]

Sounds like a prox switch issue. Prob reading front and back at same time. Entrance end prox switch should only light if unit is near very end of track (nearest entrance)

 

[M7T]

Exit travel limit not on, could be:
1. Bad exit travel limit sensor.
2. Gantry messing up pulses, exit limit should be read always at pulse 050, caused by:
a. Excessive friction during travel.
b. Track worn out, usually by the home position.
c. Side brush bristols getting caught when traveling (install an extra cover by the ES idle wheel cover, to keep bristols up).
d. Bad Idle wheels or bearings.

Next time check on Diagnostics what pulse counter is reading when F020 shows up and where is the exit travel sensor, at the flag or before.

 

[gomerpyle]

Thanks for your replies. Just to close the loop in case anyone else has this issue.

The problem was the worn track. when the gantry moved to the home position it would then drift back about an inch and a half because the track was worn and made a slope. Grinded down the track and that appears to have solved the issue.

 

[chaz]

Yep. We have actually has a welder fill in the low spot and grind it level. With that much play on the gantry it sounds like your gear box is going to need replacement soon.

thanks for posting the fix….always helpful

 

[gomerpyle]

Exit travel limit not on, could be:
1. Bad exit travel limit sensor.
2. Gantry messing up puses, exit limit should be read always at pulse 050, caused by:
a. Excessive friction during travel.
b. Track worn out, usually by the home position.
c. Side brush bristols getting caught when traveling (install an extra cover by the ES idle wheel cover, to keep bristols up).
d. Bad Idle wheels or bearings.

Next time check on Diagnostics what pulse counter is reading when F020 shows up and where is the exit travel sensor, at the flag or before.

How do you check the Pulse Counter? My problem has come back. It almost always fails on the last pass with the dryer. Once it completed but then travelled half way down the track and thought it was in its home position and ready for the next car.

 

[M7T]

P
ok
Down to Diagnostics
Module GAN
First group of 5 digits is the pulse position
Should be on 00050 when reading exit travel limit
Reset the Gantry and record what is your home position pulse.
Next time that stops, check what pulse is reading when shows the error and where is physically the exit sensor (at the flag, passed the flag, before the flag)
That will give you an idea if you are loosing pulses or the exit limit sensor is bad.

Gantry with OBD usually worn out the tracks quick, also the rear idle wheel or bearings.
Are your bearings properly grease? Do you hear excessive friction along the gantry travel?

 

[gomerpyle]

Turns out the sensor at the exit side had gotten damaged. From the track getting ground down. It was sending a bad signal. Again appreciate all your help as I learn how to diagnose this thing

 

[chaz]

Turns out the sensor at the exit side had gotten damaged. From the track getting ground down. It was sending a bad signal. Again appreciate all your help as I learn how to diagnose this thing

ah….as I thought! Thanks for letting us all know.