QuestionQUESTION: I have a 99 trans am LS1/ 6 speed. Problem started out being intermittent but now is permanent. When I turn the key, nothing happens. Battery voltage does not drop. I have unplugged the vats wires coming from the lock cylinder and used an tester in the 20k position with the key in every position and it reads 887, which is what the resistor in the key itself reads. I don't think it is the lock cylinder. Can I swap the BCM without any reprogramming? Is the BCM behind the glove box? Where is the theft deterrent relay and can I use a jumper wire to bypass it to send power to the starter solonoid? Any suggestions would help!
thanks
steve
ANSWER: Hey steve:
Well first off when you try to start it does the security lamp come on or flash? It's not the lock cylinder if you read the resistance for the key through the wire. when you try to crank it did you check for "crank" volatge at the starter motor? If no voltage then you more than likely do have a theft issue. The relay is under the hood by the battery. The bcm is under the dash by the blower motor. You can jump the relay to make the car crtank but it will not run because the bcm sends a go no go signal to the engine compouter to allow the engine to run. Yes the bcm needs to be programmed to match the engine computer. This is a job for a trianed technican. That programming can only be done by a gm dealership or an ac delco repair shop. A scan tool is needed to see what is going on in the system. Other wise you are just gusssing and threowing money out the window. Hope that helps. good luck :)
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QUESTION: The car sat for a few months when I moved recently. When I tried to start it, no go. I turned the key a couple hundred times and one time I heard the starter clicking due to the low battery. It tried, but didn't have the juice. The following weekend I charged the battery and turned those keys ( 2 keys- tried both repeatedly) about one thousand times with no luck. NO EXAGGERATION. I used a hypertech scan tool to pull any error codes but there weren't any. The security lamp flashes when the door is open and does not change its rhythm when the key is turned. When the door is closed, the lamp does not flash at all. I have not checked for crank voltage at the starter yet. I will do that this weekend. The problem was intermittent before, so I think the problem lies elsewhere but who knows. I changed the pcm with a newly programmed unit. No change. The signal the bcm sends activates the injectors, and the relay sends power to the starter solenoid right? Can the bcm signal be duplicated? If so, when I jump the relay, it should run, correct?
thanks
steve
ANSWER: No that sisganl can not be mimicked. That car uses what is called class 2 data where the computers/modules are tied together by a single wire and they share that data from all the modules on the same data wire so the BCM send that signal down the data line and the ECM sees what it's looking for and then it allows the fule to be enabled when the car is being cranked. The pcm/bcm have to be a matched pair if you swaped the pcm with another one they are not in sync and it will not start! the programming proceedure sync's thm all totherd it's called vehicle theft deturant learn. You may have added to the problem here. first and foremost check for crank voltage at the starter motor It may just have a bad starter and not anything else. the security lamp flashing with the door open is normal. those afetrmarket scan tools are not all that great they sometimes are too genaric and thye can's read all the data needed and the usually will only read the engine computer and not any of the body controllers unless it's a high priced scan tool likr a snap-on or mac scan tool.
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QUESTION: I am going to see if the local auto part store rents scan tools. It is difficult for me to get underneath to check the crank voltage so I was going to jump the relay to see if it turns over. Could you be more specific as to the location or identifying marks/numbers of the relay?
thanks
Steve
AnswerThe relay is under the hood in the relay center/fuse block.
Here is the trouble chart for cranks will not start. The problem is it's actaully a 5 coloumn chart but it doesn't show up like that when I cut and paste it. But here it is none the less:
Starter Solenoid Does Not Click
Step
Action
Value(s)
Yes
No
1
Remove the starter relay from underhood electrical center 2.
Connect a test lamp between the starter relay terminal C6 and B+.
While observing the test lamp, turn the ignition switch to the START position.
Does the test lamp light?
--
Go to Step 2
Go to Vehicle Theft Deterrent (VTD) System Check
2
Connect a test lamp between the starter relay C4 and ground.
Does the test lamp light?
--
Go to Step 3
Go to Step 4
3
Connect a test lamp between the starter relay B4 and ground.
Place the transmission in PARK or NEUTRAL (automatic) or press the clutch pedal (manual).
While observing the test lamp, turn the ignition switch to the START position.
Does the test lamp light?
--
Go to Step 5
Go to Step 6
4
Repair the open in circuit 2 between the starter relay and S183.
Is the repair complete?
--
System OK
--
5
Install the starter relay into underhood electrical center 2.
Disconnect circuit 6 (the PPL wire) from the starter solenoid.
Connect a test lamp from circuit 6 to ground.
Place the transmission in PARK or NEUTRAL (automatic) or press the clutch pedal (manual).
While observing the test lamp, turn the ignition switch to the START position.
Does the test lamp light?
--
Go to Step 8
Go to Step 7
6
Check for an open or poor connection in circuit 1433 from the starter relay terminal B4 to the transmission range switch terminal F (automatic) or the clutch pedal position switch terminal B (manual).
Check for a poor connection at the transmission range switch (automatic) or the clutch pedal position switch (manual).
Check for an open in circuit 1035 from the transmission range switch terminal E (automatic) or the clutch pedal position switch terminal A (manual) to C200D.
If OK, adjust or replace the transmission range switch (automatic) or the clutch pedal position switch. Refer to Park/Neutral Position Switch Adjustment , Park/Neutral Position Switch Replacement or Clutch Pedal Position Switch Replacement .
Is the repair complete?
--
System OK
--
7
Check for a poor connection at the starter relay.
Check for an open or poor connection in circuit 6.
If the connections are OK, replace the starter relay. Refer to Starter Motor Relay Replacement .
Is the repair complete?
--
System OK
--
8
Check circuit 1 for a poor connection at the positive battery terminal and the starter solenoid.
Check for an open in circuit 1.
If OK, replace the starter. Refer to Starter Motor Replacement .
Is the repair complete?
--
System OK
--
Hope that didn't confuse you anymore a genaric scan tool is NOT going to help you out most of them only read engine data unless you get a good snap-on or mac scanner.
