High-Line CTM VTSS or bad ECM

[dieseled]

99 auto 4x4 EZ .......

Had a bad ecm , po 1689- 1698 ,after testing wiring , inj pump ....needed to replace ecm

I kept this ecm for future repair and ordered a rebuilt , paid core , wanting to have a backup.

 

Recently received & installed a rebuilt ecm from ACS , ran good .no apparent issues

 

I`m doing a 20 year makeover list of things including turbo , exhaust brake , manifold , power steering pump and vac pump

While having the bat disconnected for a few days at a time , and then re connecting it , I have three times had the same thing happened

I go to start it ,key to run, WTS  comes on fine ,cluster illuminates fine , LP  does its short 2 sec blurb , I go to bump the starter to check for LP 25 sec and its not there , crank it and no start ,no codes

 

The first time it happened I tested  LP  by running it , powering it at the ecm plug - with it disconnected  , runs fine, its a fass w/ relay , tested  run start power to ecm , checked inj pump........ switched to the bad ecm to see ? put the new ecm back , and it was fine again , started ,LP 25 sec ok,

I was not paying attention to locking unlocking drs , and few days had gone  by

 

Second time after bat disconnect ,worked on things and reconnect, it happened again no 25 sec LP and no start ,same thing , disgusted I locked the truck , with key fob, batts still connected

Go out the next AM with a list of thing to test in my mind ,unlock with fob and its fixed itself , started .

 

Third time same thing, batts disconnected a few days , finish the new vac pump- power steer pump install , grit my teeth ,connect the batts , no 25 sec LP , no start

After pulling ecm, testing for bat voltage at the no knock on inj pump that can keep it from running and every other thing I could think of I started looking in the FSM at the CTM - central timer module , I`ve had this truck almost since new and have never knew it to have a VTSS- veh theft sec system , but remembered from just doing a heater core and dash mine has 2 plugs ,so its a high line , reading about setting off the VTSS by locking the doors with the hood unlatched to access the batts , un- hooking the batts then using the key to unlock the drs while batts are disconnected then re-hooking the batts and trying to start  the CTM send a no start to the PCM .them presumably to the ECM , if you have VTSS

Same thing happens it says if the batts go dead after VTSS is set  and you key open the drs and try to jump start  , it will go into no start and you have to disarm by locking and unlocking the drs with key or fob , but it says security lamp will flash horn and headlight flash to let you know the truck was tampered with.

 

I don't have a security lamp in the cluster , and the only time Ive ever had the horn honk and the headlights flash is when Ive hit the panic on the key fob

 

I put the newer ecm back, reconnected the batts , locked and unlocked the drs with the key fob as the FSM says to disarm the VTSS that I don't think I have and it started, LP runs as it should ????

 

I tried to recreate the no start by disconnecting batts  w/drs locked , opening them while disconnected and re connecting batts without the disarming lock unlock of the drs but it started anyway

 

Now I`m left wondering if  I have a glitch in the ecm or a CTM that is partially enabled to no start

In between no start times while batts remain connected the truck seems fine , but I haven't gone far in it , in case the ecm craps out

 

Question for anyone that does have the full VTSS  , when its in a no start condition do you have WTS and cluster illumination and 2 sec Lp w/key to run , but no 25 sec LP w/ starter bump

Edited May 21, 2019 by dieseled