Hey guys my rigs been acting weird electrically lately it sat for 9 months while I was saving for a new turbo setup. 

Now that its up and running im having several what I suspect are electrical issues here are what I think may be the symptoms of my ecu going bad( rough idle at peak high idle rpm, lift pump not cycling when I turn the key on or bump it) I do have fuel pressure while the truck runs It takes longer to start now that I dont have pressure before start up.

 

I've read similar threads but saw no resolutions

 

The other issue im having is my od, it stopped going into overdrive by itself (lock up switch did the trick for a few months) now even in lock up it wont fully lock up tach only drops 1-200 rpms. I suspect a bad apps because of an intermintent dead pedal. 

Need info off your truck, any codes present, did you charge batteries before starting the truck after sitting that long. At first glance my suspicion is batteries were low, you fired it up and let alternator do the charging along with grids cycling. This is just a suspicion and just a wild guess, you've burned up one or more diodes in alternator sending AC ripple and might of damaged your ECM.  Is your wait to start light comes on right away with key on.

I apologize I thought my details were in my signature...99 eclb 4x4 auto fass 150 feeding my vp. But yes I did charge it I got a funny ecu code two weeks ago I forgot what it was though. Wait to start comes on and I can hear the grid heater

1 minute ago, shanechrystall said:

Wait to start comes on and I can hear the grid heater

 

Instantly with the key being turn on? Any delay time wise?

Edited March 8, 20187 yr by JAG1

Id say a delay of about 10 seconds

1 minute ago, shanechrystall said:

Id say a delay of about 10 seconds

 

That condemns the ECM it is failing. This also points out there is excessive AC noise from the alternator. 

Found a good used one local to me for 100 bucks saves me a little money for a new alternator   just wanted your guy's thoughts before I pulled the trigger. I'll let you guys know how it goes .

Test the alternator before using it. $100 for bit more you could get a new stock alternator.

 

As for the ECM there is no new ECM any longer you have to have your rebuilt. 

 

No no I found a good used ecu for 100. This alternator is a year old still looks new ( considering it sat for 9 of those 12 months). Now that I think about it the truck started acting weird after I replaced the altertnator last go around ( reman from oriellys) I'll bring the alternator in and see if they'll warranty it out and have the new one tested before I leave.

4 minutes ago, shanechrystall said:

No no I found a good used ecu for 100

 

Make sure it's exactly the same there is over 52 different versions of ECM per year!

 

5 minutes ago, shanechrystall said:

This alternator is a year old

 

My last alternator only lasted 4 months. That doesn't mean anything now test the alternator for AC noise levels.

Most of the time they can't test failed diodes at part stores, you'll have to do it yourself or take it to reputable Starter Alternator Rebuilder. 

I've found that most part stores can actual test for ac noise to some degrade or another. Like my last time was at a AutoZone and the clerk had a simple hand held device just clips on the battery tested the system while idling. The tool failed the alternator but never gave a voltage measurement. Now at NAPA's they have a test stand that will repair full load AC voltage typically around 1.00 to 1.20 AC volt range for good alternator under full load. Another alternator shop in Ontario the gent has a very expensive hand held tool that does battery test and alternator testing on the vehicle. Just depends on how much money the store manager/owner is willing to invest on tools for the public.

Well finally found a used ecu that isnt 6 hours away same year auto trans but its out of a 2wd....will it matter?

I don't think it will matter on the 2WD or 4WD being the module that watch for that is the ABS module. I'm pretty sure the ECM doesn't care.

Got the ecu off of a 2wd. Gave 350 for it, didn't fix my initial issue. But it did solve most of my dead pedal issues that I thought a new apps would...throwing a new apps and radiator on today might as well thouroughly go through lift pump wiring even though its operating fine while truck is running. If I dont have any luck today im gonna take it in to a shop and get bent over L O L

So what issues remain?