The word "coolant' comes on on the odometer screen

if your refering to the odometer lights going out this happens alot I see. one of the circuits on the back of your cluster shorts and actually gets pretty hot then some times tapping your odometer reset gets it back on usually only a temp fix :O( I read a few years back that odometers are warranteed for life by buick. dont quote me on this as it was about 8 years ago and may no longer pattain. I had mine go out. bought a new one on ebay and 2 years later say thing.

Check for coolant temp sensor fault, It will affect cold start and idle. It controls open loop mode in the ECU (cold, high idle, open loop) Perform an OBDII scan of the stored fault history. Also make sure coolant level is correct.

you could faulty themostat or engine coolant temperature sensor faulty do a code scan see what code come up.

The most likely reason your display is reading gas cap is that you have an unsolved evaporation code. Most of the time simply replacing the gas cap will fix the problem, but since you have already done that there is a whole list of other things you could check. I would start with your hose that runs to your tank from your fill spout. It is possible that it has a small crack in it. Or it is even possible that one of your injector O rings has gotten bad. The bottom line is that evaporation codes are very hard to pin point and usually do not cause any problems at all. So if you decide to do nothing and not spend any money on the problem you will probably be just as well off. Well that is other then being annoyed by your gas cap light. I hope this helps you out, and if you have any other questions please feel free to ask.

Make sure there is no air in the system, take the radiator cap off and let the engine idle for half an hour, as the air comes out the coolant will go low, ad more coolant and then close the cap on also make sure the resevour bottle is at its mark.

it is probably just a burnt light on the dash for the a/c and the odometer, as for the low coolant light if the car jhas more than 100,000 miles on it you need to get the coolant flushed that is all the light is warning you about.

May I first ask: Is there any aftermarket electronics, such as security and/or remote start installed?

Are you referring to to odometer? if so, you will need to remove the gauge cluster and unplug the odometer harness and re-insert to make a better contact. Ford such as the expedition and f-150's are bad about the mileage or odometer going out and then sometime it will come back on. I just removed mine and had t do the same thing. Have you had the check engine code pulled to see what the problem area may be. You can usually get the code pulled at a local Auto Zone. The check engine light don't always mean that you have a serious problem. As long as the light stays on you are usually good , but if it starts blinking, then it's a more serious problem. Are you experiencing any problems from the truck that you can tell?

Does it look like an engine? It means you have a problem with the engine. Those vans don't have a low coolant sensor.

Usually that light stays on when you are over due for oil service, but since you state its only staying on for a short period, it might be close for the counter to reach zero miles. What I can suggest is to try and reset the counter for your maintenance light. here is hondas most typical way to resest...." insert key in ignition switch, turn key on to "run" position, do not start the car. with out taking key out return key back to "OFF", now press and hold the odometer trip reset button. while holding button turn the key back ON. Keep holding until you see the light blink/flash or on some models in the odometer window you will see the actual counter reset.