Low Coolant Sensor

[swebster]

The first thing you guys need is the service manual ,period.

Scott, I appreciate the need and benefit of a proper service manual. If you ever get the chance to look at a manual for a classic airstream motorhome you'll see why so many of us rely on the collective experience (trial and error) of other owners to troubleshoot and diagnose these issues.

I have both the P30 manual and the Airstream Motorhome Manual and neither addresses these circuits very well. At best you have a wiring diagram for the coach and dash cluster, but it stops where it meets the chassis. The chassis manual diagrams don't assume any specific coach built on it, so there is a gap in the manuals - which is why we do what we do - share experiences and glean the best possible solution based on the total experience of the group.

Despite the lack of a manual, it is this forum which more often than not help me solve this type of issue on my coach. While most of us are amatuers at this (along with a few valued professionals) we manage quite well using virtual shop talk to gain the knowledge require to keep things working on these old coaches.

The contacts inside the coolant bottle have to cause a GROUNDING! of the wire to the dash light to turn it on.

Here is something I can't get my head around and perhaps your experience can shed some light () on it. You mentioned that the light comes on when the coolant in the overflow connects the two contacts and complete the ground circuit. The confusion I have with this concept is that this is a low coolant light which comes on when the coolant level drops below the contacts. Grounding the circuit would need to trip a "default on" relay to the disconnected position for this light to work correctly. Am I missing something?

[guy99]

Scott,
First let me thank you for taking time to help us with this problem. I have read your post carefully (and with hope since this problem is a major annoyance). But I don't think our dashboards and coolant sensors are set up as you describe.

As Steven described, neither the Airstream manual nor the Chevy manual have been helpful. I think we're stuck figuring this out on our own. Maybe if we all put our heads together we can.

I will try to take and post some pictures later today so that those of you who don't have access to a Classic Motorhome can see what we're dealing with.

Guy

[Robfike]

My 345 does the same thing with the Washer Fluid Low light. My volt guage shows a lower reading as I turn on more equipment. (Engine running) If I check voltage with a volt meter at the battery, or cigarette lighter, the voltage shows normal. At first I was worried that the alternator was not able to keep up with the load, but it is just a lousy indication.

[guy99]

I spoke too soon about posting pictures. I'm in the throes of installing a new entry door for our stationary home. Of course we choose a size different form the original. I'm glad no inspector will be seeing the framing I'm doing.

Anyways, it will be a few day until I find time to remove the coolant bottle to get good pictures.

Has anyone checked out their voltage limiter?

[swebster]

stationary home

Makes me want a license plate for the Airstream which reads, "My other home has a foundation".

[overlander63]

Originally Posted by guy99

Has anyone checked out their voltage limiter?

The part is not available in the aftermarket. That would have been too easy. My next call will be to the commercial truck parts guru at Chevrolet.
Here is a photo of a Ford limiter, GM is similar:

[ericjan2]

It seems I'm having the same problem on my 87 290 coach. Light on, light off. Very frustrating. When it comes on I tend to hit the panic button. Don't want to be stranded in the desert in the heat! Under the hood a previous owner has taken the wires and attached them to one another with a screw. I guess to complete the circuit, because it probably frustrated him also. Green wire connected to white which is grounded to body. Is this my sensor wire? If so where should the green wire go to?

[guy99]

I was never able to get this to work. I suspect a problem with the circuitry in the dash.