I would like to remove the electric air gauges from my dash and replace them with direct air operated gauges reading direct pressure from the front and rear air tanks. Number one question, how do I remove the old gauges? I find a long screw with a nut on it between the data terminals. Neither 1/4 inch or 5/16 nut drivers do not fit the nut. Would this be holding the bezel on which is holding it to dash panel? Or is there another secret?
1/4" is 6mm 5/16" is 8mm try 7mm
I guess yours are different
Yes, mine are different. I have a light bulb of course and two data wires. According to my schematics, the wires come from a box that gets its data from according to Foretravel a "Air Pressure SW"
I will eventually figure out how to remove the existing air gauges. My coach does not have air line running from the tanks to the dash area like some others. Is there any reason I cannot remove the "Air pressure SW" from each tank and run an air line from that location directly to my new VDO gauges (Air)? The bung in each air tank for the Air pressure SW is only used for the SW. The SW only sends data to the Blue/black/purple or whatever box which is non functional now anyway.
What is your plan for the low pressure warning lights and buzzers
Actually since the gauges one reads zero and the other will go up to about 30 #. When I know there is more like 120# in each tank, I guess the low pressure alarm is continuous. I do have a sw to cut the dinger off. But then I cannot hear my blinkers, so Where does the low pressure alarm come from? I would guess it has to come from the mystery box since there are no other connections to the Air Pressure SW. Any suggestions?
No, no reason other than it's probably a lot of work. Found the post by Roger (linked below) where he did exactly that. I thought I remembered an old post where he gave some details about removing the stock gauges, but I can't find it...
02 U320 Air gauge stopped working (https://www.foreforums.com/index.php?topic=37921.msg366674#msg366674)
Links in his post are dead, so I revived them:
150 PSI Mechanical Air Pressure Gauge, "Front", 12V - VDO Instruments (https://www.vdo-instruments.com/product/150-psi-mechanical-air-pressure-gauge-front-12v/)
150 PSI Mechanical Air Pressure Gauge, "Rear", 12V - VDO Instruments (https://www.vdo-instruments.com/product/150-psi-mechanical-air-pressure-gauge-rear-12v/)
150 PSI Mechanical Air Pressure Gauge, 12V - VDO Instruments (https://www.vdo-instruments.com/product/150-psi-mechanical-air-pressure-gauge-12v/)
Thanks Chuck, I have read and reread Rogers posts many times. His coach had airlines from the tanks to the box, so easy to extend directly to the gauges. My coach does not have air from each tank to the dash area. But now after reading again(Thank you very much) I see this statement from Roger "What most of us have done is replace the gauges with direct read mechanical gauges with an air line h (1/8" or 1/4") connected to the tanks where the pressure transducers were to the tank." exactly what I hope to do. As far as the low pressure alarm, I am going to have other indications that tell me I have low air pressure. My brakes will be on for one thing. I always turn the dinger off anyway when I am waiting for air pressure to build. I sometimes forget to turn it back on but remember when I use my blinkers as they are hooked up to the dinger for us people with OLD ears.
That white ring unscrews so the gauge will come out. It is very tight. The last one I did, I split the white ring with a multi tool.
If you really wanted to have a audible or visual (or both) indiction of low air pressure, it would be pretty easy to connect a pressure switch to one of the air lines from the tanks to your new mechanical gauges. Just put a "T" on the tank outlet port. Pressure switch and new air line connect to "T".
On my old (mechanical) coach the low air pressure signal originates at two pressure switches installed in the air lines going to the brake (treadle) valve. They are mounted under the floor below the driver seat. They are both Bendix 228750, which activates when air pressure falls below 60 psi. You could run the 12V signal from this switch, or something similar, to a buzzer or light (or both) mounted under your dash.
228750 by BENDIX - LP-3 Pressure Indicator (https://www.finditparts.com/products/3451510/bendix-228750)
LT403....Cleanest inside dash compartment I have ever seen!!!!
Yes, I sure wish my black box had the airlines as your blue box does. (Jealous)
Yes they don't have air lines till you add them. Adding redundant visual an audible warning are a DOT requirement. Using brakes isn't a good idea IMO.
I have decided to replace the air pressure SW with a similar low pressure sender that will close a connection to a visual and audible alarm for each tank just to keep everything functional as designed or better. I will be removing the black box so my existing dinger should only sound with my turn signals. Thanks for keeping me on track.
I have been examining the schematics for my coach. I find the black box on print B2179 with a date of 10/31/01. Seems there is a connection to most of the dash gauges and to the ECM. An alarm signal combines both airs with a transmission temperature alarm signal supplied also. At this point, looks like the black box will need to remain connected. Unless I my reading is in error.
Herb, wondering how you made out on this project since I'm in the middle of this myself. Did you figure out how to remove the existing gauges by unscrewing the white barrel on the back side? Mine came off pretty easily. I have routed new 1/4" airlines from the air tanks to the backside of the dash. I'm going to install the existing Stewart Warner pressure transducers into 1/8" brass street T fittings and connect the new air line to the T so I can add new mechanical pressure gauges while keeping the original electronic gauges installed. Routing the tubing wasn't too difficult depending on how particular you are about keeping it bundled with the existing wiring and airlines (I'm picky) and it is pretty dirty working under there. I was able to push the tubing up through the floor behind the steering column following all of the other wiring and airlines that are sealed with expanding foam. I would like to know more about the gauges that you used and if you installed low pressure switches with a warning light and audible alarm.
I removed the non working senders from the tanks and fitted an air line from each tank to the dash area similar to how your ran yours. I hooked the two air lines up to VDO air gauges replacing the electric OEM gauges. The VDO gauges were an exact fit for the OEM gauges. The white "nut" holding the OEM gauges came off fairly easy once I learned how it was holding the gauges. I have two pressure switches for each tank that I plan to Tee into the lines behind the dash to a combo light buzzer. Electrically, the pressure switches will provide a ground for the combo light buzzers which will mount into holes drilled in the lower dash.
Amazon.com: Air Pressure Switch 70-100 PSI Pressure Switch 1/4"-18 NPT 24V... (https://www.amazon.com/dp/B07XYHSDZ1?ref=ppx_yo2ov_dt_b_product_details&th=1)
Amazon.com: Buyers Products BL10 Buzzer Light : Automotive (https://www.amazon.com/dp/B01CIO8E5S?psc=1&ref=ppx_yo2ov_dt_b_product_details)
https://www.napaonline.com/en/p/BK_7011734?cid=paidsearch_shopping_dcoe_google&campaign=GSC-Catch-All&campaign_id=6478877959&adgroup_id=79272987338&adtype=pla_with_promotion&gclid=Cj0KCQjwk96lBhDHARIsAEKO4xZYWw8f27bxYA7bpAulN_OlwVcOfRkYKsGFrS_esRA8ov58RerTLPIaAjOTEALw_wcB&gclsrc=aw.ds&
I have the gauges hooked up now and am very pleased with the operation. I will be adding the pressure switches, and buzzer lights when I can get back on project.
Pictures to follow when completed.
Sorry to be so long getting back with your answer . I have been occupied on other projects that have kept me away from the coach. Sure wish I was in that lady and some place cooler than HOT HUMID Texas.
I'm having trouble locating the VDO gauges (from reply #7) with black bezels in stock anywhere. Did you get the gauges from NAPA with a chrome bezel? Right now I have temporary air compressor type gauges installed until I can source the right panel mount gauges. I will add the low pressure switches and buzzer/light as well but one step at a time.
Got to tell you that I put the chrome bezel gauges in my dash and I personally do not see it as a problem. I also had trouble finding Front and Rear, so I used the generic one for both gauges. I may or may not put a label on. I know the top gauge is Front. I am sure I can locate a small Front/Rear sticky back label for the glass. I used to do sign work.