louuu

Everytime in the morning when I turn on my 2002 Type S TL (Only when its cold out) The car goes into limp mode and throw the CEL Code P1607:
ECM/PCM Internal Circuit Failure
When I leave the car running for a few minutes to warm up, I turn it off.. start it back up and its back to normal. The CEL turns off aswell.
It wont act up for the rest of the day...
I am only getting this problem with the temperature outside is low.
I know my alternator is doing bad, but is it the reason why my car is doing this? Or has my ECU just gone bad or something?
Thoughts? Thanks :P

fsttyms1

The alternator could very well be causing the issues. Id replace it if it is bad. If it continues to happen after you need a new ECU

louuu

Yeah I agree with you, I think its the alternator thats failing under cold weather conditions and not giving the ECU proper votage...

Incase I need to replace my ECU, is it just plug and play if I buy a used one? I have an 02 Type S

01tl4tl

with strange codes and symptoms like yours- first thing I say is `low voltage cause false codes`

its more likely low battery voltage from failing alt,,
get the charging system tested for free at parts stores

ck auto recycling yeards (junkyards) for a good alt,,I can guess they are pricey like most of our parts, even rebuilt at parts store
ck autozone type places for price comparision
Good Luck!

01tl4tl

remember people: the car runs off the battery stored juice,,its drawn from as needed to run all the engine sensors and electronics- fuel injection, computors etc

The alternators job is to replace the juice taken from the battery

If the batt is weak it will lose volts overnight- cold really gets them hard, plus the additional winter loads of seat heat, headlights etc mean more draw and replace happening

When you start the car- the starter takes a LOT of amps from the battery
Running the car at idle when cold doesnt recharge the batt--takes approx 1500 rpm to make enough alt output to cover operating use- and replace loss overnight and starter useage
So thats your CEL at idle warmeup--stop sitting!- the car warms faster when in motion! ecu programming etc etc,,
as soon as it will freely rev to 2000- about the time it takes to buckle up, set cd and nav.. its time to get going

totaledTL

How old is your battery? Is it sealed or can add (distilled) water if needed? Any corrosion on the terminals? Had it load tested?

When it's cold out people are going to let them idle to warm- human nature. Esp. if remote start is installed.

01tl4tl

I know- but I can share what I read in the owner book and hope for the best!!

arne.kaplan

what was the final fix for the p1607

I have a 01 cl s type with the same problem

Karanx7

iTrader: (2)

Welcome to AZine.

The code is basically saying that there is a problem with the ECU signal. If all of your electrical system is fine and working properly, then the ECU is bad. You can replace the ECU, but I would just recommend getting a used ECU, as they are pretty cheap now.

First diagnose the electrical system: battery, grounds, terminals, alternator.