Transmission and Engine Temp gauges not working

[myway02]

A 2002 Monterey on a Magnum Chassis , would anyone know why the Transmission and Motor temp. gauges would quit working? I tested the voltage and it' OK. The ground has also been tested. Not sure what the reading should be from the sending unit.
+ I only found four fuse's in the battery bay for the chassis, breakers, and relays in electrical bay (left side under driver seat) Could there be any more fuse's elsewhere? I have no blueprint for my electrical. Thanks

[Gerald Farris]

There are several questions;
1 Did both gauges stop at the same exact time.
2 Does your coach have an engine monitor (Silverleaf). and does it read engine and transmission temperature.
3 Does your coach have two temperature sensors for engine, and two for the transmission (one for the dash gauge and one for the computer) like most coaches.

Most dash temperature gauges are wired by running fused 12V in one terminal of the gauge and out of the other terminal to the sensor that grounds the circuit with varying resistance, depending on the temperature. So if yours is wired like this, and you have 12V to the temperature gauge, you do not have a fuse problem, but a wiring, sensor, or gauge problem. To determine which one it is will require answering the questions above and some testing.

Gerald

[myway02]

There are several questions;
1 Did both gauges stop at the same exact time.
2 Does your coach have an engine monitor (Silverleaf). and does it read engine and transmission temperature.
3 Does your coach have two temperature sensors for engine, and two for the transmission (one for the dash gauge and one for the computer) like most coaches.


 Not really sure about the sensor for the engine monitor, I asume they are in the electronic control module of the ECM. I know I have power at the gauges but not sure about the sending unit.

Both gauges went out at the same time and I do have an engine monitor and shows that both are working.
So far all I have found on the chassis are four fuse's and all working.  :-/ Thank you Larry

[Gerald Farris]

The engine coolant temperature sensor is not in the ECM. It will be screwed into the cylinder head or coolant outlet near the thermostat. You will need to locate the sensor for the dash gauge (not the one for the ECM), and check it for voltage. If there is no voltage, you have an open circuit either in the wiring or the LF electrical bay. An open circuit is probably the problem, since you said that you lost both gauges at the same time, and when you find the problem with one gauge the problem with the other one will be obvious. But that is only a guess since I can not see the coach.

If you are not experienced in electrical diagnosis, you probably should go to a good repair shop like Beaver Coach Sales because improper diagnoses procedures can cause expensive damage. Or you can just watch the temperature readings on the Silverleaf.

Gerald

[myway02]

Gerald thank you for your help. I agree with you that I must have a open circuit on the positive side. I'm still lloking for the magic door with more fuses besides the 4 in the battery bay. I think what happened was after winterizing the motor home the prosine was on equalizing. During that time the brake pedal was hit 2-3 times.  The police officer reminded me that I did'nt have any brake lights at the storage garage. I checked the brake lights and both of them were burnt out, I mean black burnt. I don't have the schematic for the Magnum Chassis, would like to find one. I was told the prosine on equalizing will sometimes go up to 19 volts, at that time I lost both gauges. Again thank you for your help and I will let you know of any progress, Larry