Chevrolet Repair Questions? Ask a Mechanic for Answers ASAP
Have you checked the fuel pressure with a guage?
thought fuel pressure leads tu fuel pump probs?
That will be the first thing you need to do. You can at least check the fuel pressure regulator and make sure there is no fuel in the hose. Verify that fuel pressure, while cranking in the mode of hard start, is 60+ PSI You will need to eliminate this first.
VEHICLE THEFT DETERRENT (VTD) DESCRIPTION AND OPERATION The vehicle theft deterrent (VTD) system functions are provided by the theft deterrent control module. The VTD system prevents vehicle operation if a valid (learned) transponder PASS-Key®III (PK3) ignition key is not used to start the vehicle. The theft deterrent control module has an exciter that is part of the theft deterrent control module as an assembly. The PK3 key has a transponder embedded in the plastic head of the key. The exciter is an antenna which is made up of wire coils which surround the ignition lock cylinder. The PCM enables the engines starter and fuel delivery system when it receives a valid (learned) password XXXXX the theft deterrent control module via the class 2 serial data circuit. The components of the VTD system are as follows:
THEFT DETERRENT CONTROL MODULE Vehicles with steering column mounted ignition switches have the exciter integral with the theft deterrent control module which is located within the steering column. Vehicles with instrument panel mounted ignition switches have exciter modules separate from the theft deterrent control module with the vehicle wiring harness connecting the two. The theft deterrent control module for vehicles with instrument panel mounted ignition switches is located within the instrument panel. The theft deterrent control module can learn up to ten keys (transponder values). The theft deterrent control module uses the following inputs, battery voltage, ignition switched voltage and ground circuit. The theft deterrent control module uses the following outputs, password XXXXX with the powertrain control module (PCM) via class 2 serial data circuit. When an ignition key is inserted into the ignition lock cylinder, the transponder embedded in the head of the key is energized by the exciter coils surrounding the ignition lock cylinder. The energized transponder transmits a signal that contains its value, which is received by the theft deterrent control module. The theft deterrent control module then compares this value to a value stored in memory and performs one of the following functions:
IMPORTANT: If the PCM is unable to communicate with the theft deterrent control module (loss of class 2 state of health) after the vehicle has started, the module will consider itself malfunctioning and enter a fail enable state and illuminate the Security Indicator. The vehicle will not stall or stop running. If the PCM is in a fail enable state when the ignition is turned to OFF, it will remain fail enabled until the next time the vehicle is started. If the PCM is fail enabled the theft deterrent system is NOT active and the vehicle will start. The PCM will remain fail enabled until class 2 communication with the theft deterrent control module is restored. POWERTRAIN CONTROL MODULE (PCM) The powertrain control module (PCM) verifies that the password XXXXX from the theft deterrent control module via the class 2 serial data circuit is correct. The PCM can learn only one enable password. If the enable password XXXXX XXXXX the PCM enables the starter and fuel delivery systems. The PCM disables the starter and fuel delivery systems if any of the following conditions occur:
THE IGNITION KEY (TRANSPONDER) The ignition key for theft deterrent equipped vehicles is a typical looking ignition key with a transponder located in the plastic end of the key. The transponder value is fixed and unable to be changed. The theft deterrent system uses the ignition key transponder value to determine if a valid ignition key is being used to start the vehicle. There are approximately three trillion possible transponder values. There are no visible electrical contacts. The keys may be identified by the letters 'PK3' stamped into the steel shank of the key. The theft deterrent systems use the following types of ignition keys:
IMPORTANT: Valet keys have a gray plastic end which are NOT original equipment on this vehicle. Valet Keys are available on other GM vehicle lines. Valet keys provide limited access to the vehicle and vehicle functions. Valet keys may perform the following functions:
IGNITION LOCK CYLINDER The ignition lock cylinder performs all of the functions of a lock cylinder on a non theft deterrent equipped vehicle. The ignition lock cylinder for vehicles with theft deterrent may be located on the steering column or on the instrument panel. In either location the exciter coils surround the ignition lock cylinder such that they are very close to the head of the key which contains the transponder pellet. If an ignition lock cylinder is replaced, new transponder keys must be cut to match the mechanical coding of the new lock cylinder. The new keys must be learned by the theft deterrent controller module. When replacing an ignition lock cylinder, refer to Programming Theft Deterrent System Components. SECURITY INDICATOR OPERATION The instrument panel cluster (IPC) illuminates the SECURITY indicator in the message center as determined by the vehicle theft deterrent (VTD) system. The IPC receives a class 2 message from the theft deterrent control module requesting illumination. The theft deterrent control module can command the IPC to illuminate the SECURITY indicator only when the ignition key is in the ON position. The security indicator is a malfunction indicator and does not illuminate during the bulb check when the ignition is turned to ON. If the PCM loses communication with the theft deterrent control module, the instrument cluster will also detect the loss of communication and will illuminate the SECURITY indicator. The SECURITY indicator can indicate both malfunctions (Indicator on steady) and tamper (Indicator flashing - indicating unauthorized operation). Under the following conditions the SECURITY indicator may be commanded to illuminate.
We need to determine if it is spark or fuel, so if these pressures are ok then we can look into the electrical ignition system. This also could be a plugged fuel filter.
wow!! now that you totaled confused me! I know the security light has been on lately. as far as changingthe fuel filter it looks like the whole line has to be changed does a 1998 have a chip in the key head?
The security light makes a world of difference, this may be your issue. When the car does not start does it just crank and not start or no crank at all?
then after ten min it will start
Ten min of leaving the key turned on or just come back in ten min and it works?
attempt to start wait a a few min try again try again pump it then try it again until it starts
turn on then turn off in between
i also have left it and come back and it started goofy darn truck
This could be a security issue. If the light is on then it is probably an ignition lock cylinder issue, this is where the pass key sensor is. Since the light is on this needs to addressed first. You will need to have the body control module scanned and see what the code is, this will tell us alot.
ok then what
The code will tell us which way to go. Whoever scans it has to be able to scan the body control module to get those codes. I think your ignition lock cylinder is bad, after replacing it you will have to do a key relearn. Most auto part stores will scan the computers for free, except in California.
you mean if i go to napa they'll do all this ? i'm confused
If they do free scans. Al you need to do first it get it scanned and see what the codes are. As long as you don;t live in California, Autozone or Advanced Auto will do it for free I know, but they have to scan the body control module, this is where the code will be. That will tell you which way to go. Get it scanned before anything else.
k bob then what do we do
After you get the code just right back through this thread and we can go further. Just respond here.
If I am not online I will get back to you ASAP
ok this may sound like a stupid question but how do i save this and get back in touch with you i'm just an ole nam vet just gettin by
Thanks for serving!!!!!!! I appreciate all you have done for the country!!!!!! I will switch this over to a regular question and answer then you can just respond to it.
Hi Bob I did'nt get a chance to get to auto zone had appts. at va all day but did notice when truck did not start security light was flashing when i let sit for 10 min. and just turned the ignition on light was not flashing and truck started right up!
So it has to be the ignition lock cylinder.
How esential is getting the codes opposed to just getting the repair done and how many dollars is this going to cost me (I hate to ask) Rob
k bob I think this solves my problem I guess I'll find out thanks for the expert advice and keep up the good work rob
I just recently purchased a 2004 Tahoe with 155000 miles