2002 Mitsubishi Diamante LS from North America - Comments

I have a similar problem with my Diamante 2002 model. Heater core leakage, Drive and Neutral lights flash, service engine light on. Dealer says min $3000 to fix. EBS is gone because the leakage.

Hi all.

Just like you, the transmission started acting funny for no reason. Took everything apart and there is significant evidence of coolant on the plastic that protects the ECM and the floorboard.

Everyone keeeps talking about a "transmission relay". Where is this?

I have a 2001 Diamante LS with 135K miles.

I found a local junkyard that has the ECM I have (w/traction).

I have 3 boxes in the front center of the car:

1. Air bag module (very bottom of ECM) part MR538276

2. ECM part MR514497

3. Traction control box (just below the radio mounted vertically) part MR502450.

Where is the mystery "transmission relay"?

Thanks.

The ECM (engine Control module) is also called the Powertrain Control Module (PCM). You found it apparently, under center of dash, forward of center console. In later Diamante models Mits. put plastic wrap over it to protect it from their own poor heater core gasket joint design. Very sad! The transmission control relay you asked about is also under the right side of the dash near center console. It has four wires coming out - black to ground, red/white to the PCM, orange to PCM, and white/black to the engine compartment fuse box (20A engine control fuse).

I too had coolant smell, wet carpet, in my 02 VRX with 85,000 miles. Found procedure on line and fixed it myself with $2.50 gaskets from dealer, with only partially removing dash under glove box, and not the whole dash as the dealer will charge you for. The coolant leaks right down on the PCM, which is directly under the heater core piping joint where it connects thru the firewall to the engine compartment coolant lines. Shame that a $1 poorly designed gasketed joint is the culprit for 100's of thousands of repair $$ and many unhappy customers.

Happy hunting!

Marco in Indy.

Purchased a 2002 Diamante LS in June with 86K on it. Here I am in October with 94k on it and it's time to replace the heater core. I haven't taken it to the shop yet, but everybody is explaining my problems exactly. Screw Mitsubishi, recall this crap ass vehicle. $1400 to replace some crap piece of machinery you chose to use to cut down costs? What kind of company are you running? I'm going back to American.

I have a 2002 Mitsubishi Diamante with the heater core problem too. I had read on one of the comments to use radiator leak sealer and pour it on the radiator while the engine is on and the heater is also on to circulate the sealer around the heater core until it reaches the "O" ring on the rubber tubes and seals it. Make sure to scoop out some of the antifreeze from the radiator so that the sealer will replace the the amount of the anti-freeze being scooped out. As soon as the sealer reaches the "O" rings and seals it, you'll notice that the leaks will stop, you may now stop your engine and let the sealer hardens. My Mits leaks at 70k, it's 120k now and still no leaks. Try it. Good luck.