HELP!! M, S, and D Flashing

[DiscoTech]

So, went out for a roughly 9 hour round trip today. About 3 hours into the trip, the truck has a harsh "klunk." I didn't think much of it as I was running up and down some steep hills, and just assumed that the transmission had a moment of stupidity. About 30 minutes later, it happens again followed by the M, S, and D flashing on the dash. I managed to make it to an auto parts store to have them check the battery and alternator; I assumed it was one of the two, or both. Turns out the alternator took a shit on me, but no worries, the auto parts store had one in stock. Got the alternator changed out, and continued on my way. Made it another 3 hours to my destination with no issues. About 2 hours into the return trip, same symptoms as before. Turning off the motor, and starting it again was a temporary fix that allowed me to make it the rest of the way home; it happened 2 other times on the way. I read the codes once home, and got a P0335 CPS circuit A code. Now, I just changed the CPS a week ago after it failed and left me stranded.

I'm guessing it's either the battery (tested okay at the auto parts store), the CSP (I would hope it lasts longer than a week), or something caused a new alternator to go tits up. So, does anyone have any idea what could be going on? BTW, it's an '02 Disco with 142,000 miles.

Thanks in advance!

Mike

 

[discostew]

If you didn't say it had a loud bang before the lights started flashing I would think it was your temp sensor. But you really need to get the codes out of it.

 

[DiscoTech]

The only code it threw was the P0335.

 

[discostew]

Thats a crankshaft sensor code. Depending on what scan tool your using trans faults might not be getting read.

 

[DiscoTech]

Yeah, I know what the code is, but I replaced the crankshaft sensor last week. I'm using an Autel AL619, which reads SLABS and the normal OBDII stuff.

Mike

 

[DiscoTech]

What type of trans fault could it be? The obvious one is the neutral safety switch is shot.

 

[discostew]

We would just be guessing. I guess you could hope its an xyz switch but I've never heard of it causing a bang. The bang could have been the engine loosing spark for a second due to the crank sensor fault. But that would be really out of the usual stuff too. Your gonna have to get the trans codes out of it and hope its not some kind of hard part getting ready to let go inside your trans. The loud bang is the biggest problem I would think. And maybe a code will be a good clue as to whats going on.

If its a trans temp switch fault your going to have to take the bang into consideration also. The temp switch could be working fine and its the trans overheating because of a mechanical issue.

 

[juramico]

Not quite familiar with D flashing. When my M S lights were flashing, a new battery solved that issue. The tranny couldn't shift properly due to the lweak battery.

 

[rovercanus]

The xyz switch can cause a bang. When mine went bad it would shift hard from neutral to drive and reverse. I didn't get a transmission fault but I did get a ses light.

 

[DiscoTech]

A couple people have said it may be the XYZ (Neutral safety switch) as well. The SES is normally on because of an O2 sensor, but after clearing the codes yesterday, it flashed real fast right beforw the bang and then stayed on. None of the car shops, nor either of my code readers pull trans codes, but at the amount of miles I'm at it may be good preventative maintenance to just change it out.