Front Air Sender

[Dale F]

I'm getting funny reading & alarm on my front air gauge. Coach is aired up and holds air good. I believe the sender unit is bad & I want to check it. The front & rear sender units are mounted in a tight space on the firewall by the driver. Accessed from outside. Does anybody know if the air glide generator will go out far enough to fit a slim person there to access. I haven't played with mine yet to determine an answer. Wanted to ask other TS owners if they've been able to move the genset past the factory settings on the glide. Once I get to them I want to switch the rear & front harness to see if I get the same funny read on the rear gauge if that makes sense. Just starting this process & I'm studying before diving in.

[rag_ftw]

Dale, it might be easier to start with verifying the gage is good by swapping the wiring connectors to see if the problem follows the system or the gage.

Sorry I can't help with the air glide generator.

[Dale F]

Yes, that's what I'm trying to do, but they are in a limited space area. I can take the panel that the gauges are mounted on the dash off & swap the wires there, but I thought I'd look at the outside first.

[OldHatt45]

Dale,
When you say "a funny reading" on your front air gauge, exactly what is the gauge reading??? And it would also be good to provide us the rear Air Gauge reading as well.
Does the alarm sound continuously???? (as in never goes off?)
When was the last time you manually purged the air system? (pulled the lanyards?)
How long has it been since you changed your desiccant filter????


Start with these and then we can get into helping you troubleshoot what's going on.


Drew

[Dale F]

Rear gauge 125, front about 80 then drops to 60-65 when put in drive. Front gauge has always bounced around from 125 down to 80 or so. I'm told both gauges should read consistent. This time it goes down & alarm stays one, but the coach is fully aired. Rear gauge consistent.

Dryer filter changed in June. Purged I can't say. I'm going to ask my service shop if they've done it. Where are the lanyards located? I want to do that myself to learn.

I've ran the air out with the brakes while in park and the coach airs up & purges. Searched the Spartan Forum & I'm leaning toward the sender, but trying to figure out how to access so I can switch wires to see if it corrects front gauge & moves problem to rear.

[hwbuck]

not sure your year and model coach but my 2006 TSS has a pin that releases the front cover allowing it to slide forward an easy 1.5 feet. Makes access easy even if you do not our gen slide out. Buck

[OldHatt45]

Dale,
OK, that's better.


The Lanyards are attached to the automatic moisture ejectors at the air tanks. On our coaches there are 3 of them. If you can safely go under the coach, go look at the air tanks which are about 2-3 feet behind the front wheels in the center of the coach between the frame rails. You should see the lanyards attached to the ejectors on the bottom of the air tanks. Follow the lanyards to where they are accessible without going under the coach. (My coach did not have the lanyards when I bought it. I had to install them.)


Now, as to the pressure reading on the Front Gauge. It is possible that the sensor is bad, but the sensors don't generally go bad. I have attached a sketch that I made of the Air System on my coach, that I put together from the Spartan diagrams and physical inspection. On my coach, I had symptoms similar to yours. It turned out to be a Bad Main air line between the Compressor and the Air Dryer. It had a Pin Hole in it. It would allow the coach to air up, but due to the pin hole, the compressor could not keep up with the demand for air on a moderately bumpy road, so the gauge would drop and rise similar to yours.


There is a pressure protection valve that is set internally for 75 psi Open and 70 psi close. This protects the ability for the air brakes to operate. But 70 psi will not keep the suspension up and will likely set off the alarm. It takes about 90 psi to keep the suspension up. So the question is, when you pump the brakes and the pressure drops, is the suspension (in particular the Front) still all the way up??? (My front suspension dropped about 4 inches when testing this.) My rear suspension did not drop, due to the accumulator tank maintaining correct pressure. (The rear accumulator tank is between the rear wheels.)


If the suspension will come up all the way on start up measure the height of the coach. You can measure it near the front entry door. It doesn't need to be precise, just to see if the front is staying up when you pump the brakes and the air gauge drops to your 60 psi reading. (Hint: Check the Front wheel clearance when you hear the system purge.)


Hope this helps,


Drew
2003 - 40DS02

[Dale F]

Well, here you go. Went out with the son-in-law today & switched the harness on front & rear senders. Both gauges read very good! Switch them back to regular and the both continued to read very good. Played with the air up & down, brakes and so & everything worked what I consider normal. Took the coach out for a 30 mile test drive and the gauges worked very good!

I did find the lanyards. 3 of them. With steps in up position they are slightly in from the back of the steps, slightly toward axle from steps and up through a hole in the frame. Easy to see once you know. No water in any of the tanks.

Also, I was able to easily access the senders with the Genset retracted back in and the door manually opened.

[The Driver]

Brother...dirty contacts....

Excellent info all around, thanks!

[OldHatt45]

Dale,
As The Driver (Doug) said, sounds like dirty contacts. Glad the problem was simple!!!!! Would suggest cleaning the contacts with some contact cleaner or alcohol.
And maybe some dielectric grease to protect them.


Drew

[rag_ftw]

Ya gotta love those electrical problems that seem to magically fix themselves! Mechanical engineering is a lot more straight forward. When it breaks is stays broke!
Good job of troubleshooting and glad it was an inexpensive fix.