A few weeks ago while driving my "Service Engine Soon" and "Transmission Temprature" lights illuminated on my dash, the SES stayed on upon start up and the trans temp came on after about 5 minutes of driving and stayed on until the truck was sitting long enough to cool. I took it to the dealer and they diagnosed the problems by code as the knock sensor and MAF.

I picked my truck up today and upon start up the lights were off and stayed off, about 10 minutes into the drive the trans temp light came on for about 30 seconds and then stopped but then right before I went to turn my car off 5 minutes later it illuminated again.

What could be the issue? I called the dealer and they said that it could just need a day to reslove itself and that when tested and driven 20 miles after part replacement they didn't get a light and there were no codes.

 

It will not store a code for this. It could be either the temp sensor for the trans or for the t-case, and is usually a switch or wiring issue rather then an issue with actual fluid temp.

Trans temp sensor is in the trans cooler in front of the radiator, with connector at the top passenger's side.

Used to have a lot of issue with t-case sensor wiring getting corrosion in it.

 

Ok, doesn't sound to bad, I had a trans flush and they said the transmission was in excellent condition and serviced as it should be (I want to make it last as long as I can obviously) so I was really hoping it wasn't anything serious.

 

First there are only 2 reasons for that light to come on, hot tranny and or hot t/case. Unless you had another code showing up neither the MAF or cam sensor will cause this.
How was the vehicle running, was it a little rough or hard starting, was your gas mileage getting bad?
Does it show on the work order what the fault code numbers were, I think they screwed you by selling you something you didn't need.
In the future go get your fault codes read for free at a local parts store and get back to us with the actual fault code numbers, and "QUIT" going to the dealer, unless you like getting over charged.
As for your tranny light, when was the tranny, T/case and both diffs fluid changed?

 

I only go to the dealer because I have a no deductible warranty. I have an OBDll reader as well.
I've had my disco alittle over a month and upon purchase the trans and t/case were flushed and the mechanic said they were in great shape.
I WAS getting horrible MPG but I was thinking that was due to the sensors, the car starts right up, no ticks or knocks, the transmission shifts fine, no jerks or slippage, it actually runs better once it warms up. I'm thinking the temp sensor is bad because the car spent 5 years in winter weather and is probably corroded.

 

Understand regarding the warranty, what codes did you see that justified replacing both sensors?

 

I don't remember the codes but the reader says specifically what they were and it said knock sensor and bank 1&2 too lean.

 

Well prior to your mentioning the warranty, I was afraid they put the screws to you.
So how about your fluid changes, how many miles has it been?

 

In the copy of the RAVE electrical diagrams, that light can be turned on by oil temp of transmission or the transfer case. These are serious issues and they need to look at fluid levels of each. These sensors just turn on the bulb, they are not part of the OBDII diagnostic system, so no techs without gray hair might understand what to do.... people depend on computers too much, hell, I could just send out a pidgeon with a page from the RAVE if the partz vulturez had not eaten them all...

Not much way for the transfer case to log a code.....

 

I have video of the light! Just don't know how to post it.

In the 30 second video I just pulled up to a traffic signal the temp light is on for 10 seconds then goes off, then blinks in a random interval (not a steady blink, kinda like a house light bulb not quite screwed all the way in) then shuts off for 10 minutes then blinks irregularly again, then when I got home it stayed on solid for a few seconds then turned off. It's so crazy weird.

It's been less than 1.5k miles since flush of both.