1st Mar 2009, 21:14

Hi, I have a 2003 Diamante with the same problem with the heater core leak and the flashing of the neutral and drive lights. I'm going to re-run the in and out hoses to the heater core so that it's completely by-passed. Summer is coming and I'll do it when I get some time. I'm probably going to need the ECM. Does anyone know where I can get a new one? Please email me back at crazie526@aol.com Please title it 2003 diamante. Thank you for any help.

5th Mar 2009, 23:59

I have a 2001 Diamante LS, and the TCL light won't go off, but when it's cold outside it won't come on until it's warm out.

Also my service engine light is on. Any suggestions?

10th Mar 2009, 15:10

The engine light may be due to ABS/TCL system fault being set, or it may be due to something totally unrelated. Suggest you go local shop that can scan engine and ABS system codes for your vehicle and have them tell you what the fault code number (s) and description (s) are. It's only speculation as to what the problem is and why the outside temp matters until you know what part of the system is setting fault code (s). My '02 Diamante had an intermittent TCL and engine light that came on, along with ABS motor actuation shudder when brake was applied. It turned out to the passenger side rear ABS sensor was bad - a simple fix once you can find an affordable one in a junk yard. As is the case most of time, too many middlemen drive replacement part prices out of this world. Report back here what the shop told you. I have Mit. Diamante shop manual and can confirm if they told you the truth, and the actions prescribed to take to further diagnose and remedy. Good luck!

13th Mar 2009, 16:50

Well, I did it. The 2002 Diamante with the heater core gasket problem was exactly the same as many others have reported. Over the course of a couple of months, I carefully followed the 21 step process and replaced them myself. After finishing this procedure I am relieved that there is no more leak and the check engine light is off.

Takes a lot of patience...

24th Mar 2009, 10:34

I purchased my 2001 Diamante new and have 61,500 miles on it. I had the same O ring issue at 31,000 miles. However, since it was past the five years by one month, I was told it was out of warranty.

Two weeks ago I did the 60k service, which included replacing the timing belt, flushing the transmission and coolant. I planned on keeping the car for a very long time so I did all the suggested maintenance. The transmission failed last week while driving without any warning. I spent many hours on the phone and as you can probably guess, Mits would not give any assistance or consideration since it was out of warranty, even though all the maintenance had been completed. I had to come up with $2,500 to put a rebuilt transmission in the car. The shop indicated these transmissions have a problem with the chain breaking and being sucked up into the pump, causing failure with no warning.

I also had a small rust issue on the right rear quarter at around $50,000, but I was educated by the dealer and the rep and told it was not rust. Even if it was, since it wasn't through the metal (I'm assuming since I could not poke my finger through it) it would not be covered. Three claims, no help at all.

I can't even begin to tell you how disappointed I am. After reading all these comments, it appears these cars have both defective heater core O rings and transmissions. I expected much more from my first new car ever and one I paid $28,500 for and have taken care of. I called a friend of mine last week since he has a 2002 Diamante to warn him. He advised the transmission went on his Diamante last year at 85K.

This will be the last Mits. I will ever buy.

7th Apr 2009, 08:27

I added the above blog, and after a few days of getting my car back with the new transmission, the TCL light and the anti-lock brake light went on. The TCL flashes and the anti lock light stays on. It appears from reading above it is a wheel sensor. Can this really be happening???

This is the third major problem that everyone else has listed above. Is it possible the shop damaged a wheel sensor when they worked on installing the new transmission? Anyone qualified to give me their opinion?

It seems like too much of a coincidence. I'm having the shop scan it on the machine to determine the cause and what wheel if it is a sensor. If it is the sensor, how did the person above get this fixed for $200? Please respond if possible.

8th Apr 2009, 14:42

I just found out it is the right rear wheel sensor that needs to be replaced. Any idea on how it could be replaced for $200 as mentioned above? The dealer quoted me $454 for just the sensor? It doesn't appear there is much labor involved. Do they make an after market sensor? Help?

13th Apr 2009, 21:29

Another 2003 Diamante heater core victim. Replaced the O ring for 1000. Wish I found this blog before purchasing this car. Mits should at least offer me a free oil change.

15th Apr 2009, 10:53

Good luck trying to get an oil change from them. Not sure how many miles you have on your car has, but I would start saving money as it probably won't be long, and your transmission will fail at a cost of $2,500, and you will also have the TCL/Anti lock brake light go on for another $700-$800. I hope you have better luck than I did.

1st May 2009, 08:37

No transmission failure yet, 59,000 miles... knock on wood.

Two problems so far on my 2002 LS, which I bought new in November of 2001. Four months ago the Traction Control light came on. I took it to my local mechanic and he changed the right rear sensor, which fixed the problem ($600 total). Two months ago the Service Engine Soon light came on. I checked all fluids and installed a new air filter but the light stayed on. Took it to my local mechanic and he changed one of the oxygen sensors, which fixed the problem ($400 total).

I quit using the Mitsu dealership when my warranty ran out. They wouldn't fix a sticking accelerator pedal because I wouldn't adhere to the dealership's schedule of maintenance, which was far beyond Mitsubishi's schedule in the owners manual. They contended that I had allowed a build up of varnish in the throttle body and that was making the accelerator pedal sticky. I took it to my local mechanic, he lubed the linkage cable and it fixed the problem. I did protest to Mitsubishi about the dealer's unfair practices and they were reprimanded and have since closed up shop.

I just installed an air horn on the car and now the OEM horn won't work. The fuses are good as well as the relay. I might have screwed up the contacts in the horn button. I'm not going to mess with it though as I'm leery of setting off the air bag.

I love my LS and would like to find a very low mileage 2004 that is not black. I like the tan/cream color best.