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jrhorton
Novice
Jul 13, 2013, 4:04 PM
Post #1 of 9
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2003 Lesabre won't start
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2003 3800 Buick Lesabre, 3.8 L, Pass Key 3, 68K miles.
Cranks but won't start. I've narrowed it down to fuel not actuating through the injectors. The Passkey system can shut off fuel, but it seems to be working, as the security light does not flash and the dash monitor recognizes "Driver 1." Regarding spark, the HEI spark tester shows good spark. 12 volts is present and the battery remains adequately charged. Prior to the no starting problem, the battery was tested at a store under load and tested good. I also tested the ICM, it has power and is delivering same, so I have spark. Fuel pressure is good at the rail. The injector wire has voltage, but the ECM is not grounding the other wire, so the injector will not actuate. This is confirmed with a volt meter and Noid light.
Another wrinkle: I bought a code reader and it shows everything normal on my other two cars. They run good so no codes. The icons are fixed and stable. However, the code reader acts squirly on the Lesabre. It shows no codes. Three trouble icons are fixed and stable, which shows that they have been read properly. However, 5 other icons continue to flash, and never stop flashing.
(FYI, and prehaps related or not, a month ago, when the Lesabre would still start, the car ran rough for a few days, and I had trouble codes P0301 and 0201 read at Autozone (cylinder 1 misfire). The next night, because I was testing, I left a 2 amp trickle charged on overnight. The next day the Lesabre would not crank, until I jumped the solenoid to the starter. Since then the car does crank but not start.)
So my options appear to be:
1) bad ECM (perhaps indicated by the code reader acting whacky?, and the non-grounding of the injector wire);
2) bad Passkey system;
3) a short in the wiring (?).
Because of good spark and ICM function, I want to rule out the Crank Position Sensor, or should I?
Because the rest of the starting system seems normal, I want to rule out the wiring short, or should I?
This is what I'm thinking of doing: on eBay I can purchase an ECM reset to my VIN for $95, or a remote start kit with Passkey bypass for $90. My money is on the ECM.
Any input would be greatly appreciated! 
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Hammer Time
Ultimate Carjunky
/ Moderator
Jul 13, 2013, 4:10 PM
Post #2 of 9
(5578 views)
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Re: 2003 Lesabre won't start
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Here are the diagnostic tests needed to isolate where the problem is. Give me the results of every test.
Every engine requires spark, fuel and compression to run. That's what we have to look for.
These are the basics that need to be tested and will give us the info required to isolate a cause.
1) Test for spark at the plug end of the wire using a spark tester. If none found, check for power supply on the + terminal of the coil with the key on.
2) Test for injector pulse using a small bulb called a noid light. If none found, check for power supply at one side of the injector with the key on.
3) Use a fuel pressure gauge to test for correct fuel pressure, also noticing if the pressure holds when key is shut off.
Once you have determined which of these functions has dropped out,
you will know which system is having the problem.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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Discretesignals
Ultimate Carjunky
/ Moderator
Jul 13, 2013, 4:27 PM
Post #3 of 9
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Re: 2003 Lesabre won't start
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You confirm spark, so the ignition module is getting a crank signal.
You confirmed you do not have injector activity. You stated fuel pressure was good.
When it doesn't want to start are you able to communicate with your scan tool?
When it doesn't want to start, does the check engine light do a bulb check when you turn the ignition on?
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
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jrhorton
Novice
Jul 13, 2013, 4:33 PM
Post #4 of 9
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Re: 2003 Lesabre won't start
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1) good spark with HEI spark tester;
2) my noid light shows no pulse;
3) fuel pressure not checked with a guage, but good pressure at the Schroeder valve with a manual test.
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jrhorton
Novice
Jul 13, 2013, 4:39 PM
Post #5 of 9
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Re: 2003 Lesabre won't start
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I don't understand the question about scan tool. The code reader tool doesn't seem to be properly reading the system.
The check engine light does not come on. It was on a few weeks ago, due to the misfire codes, when the car would start and run.
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Discretesignals
Ultimate Carjunky
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Jul 13, 2013, 4:49 PM
Post #6 of 9
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Re: 2003 Lesabre won't start
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When you turn the ignition on the check engine light should come on for a bulb check. This is just an indication that the bulb is good and the PCM is alive to turn it on.
If the check engine light doesn't illuminate when you turn the ignition on, you have problems communicating with your scanner, along with the engine not wanting to start is an indication that the PCM is not alive.
Some things you need to do before you even think about condemning the PCM:
(1) make sure you have 12 volts on pin 16 of the data link connector.
(2) There is a circuit from the PCM that feeds power to some of the sensors on the engine and transmission. This is called the 5 volt reference circuit. One way to see if the computer is alive is to measure the voltage at one of the sensors that use the 5 volt reference. I can tell you that the TPS is probably the easiest sensor to check for 5 volts from the PCM. The grey wire at the TPS connector should have 5 volts on it with the ignition turned on. You need to check it with the circuit loaded, which means you need to back probe the connector with it plugged in.
(3)Make sure the PCM has good powers and grounds at the PCM connector. You'll need a connector pinout to find out which wires to probe.
(4) If PCM has good powers, grounds, 5 volt reference, check the TPS signal for high voltage. If the PCM sees WOT from the TPS during cranking, it will not fire the injectors.
(5) Check for crank reference signal from the ignition module to the PCM. PCM needs this signal to fire the injectors. You'll need a lab scope or graphing meter to see this signal. You could also do a bypass test using a test light to see if you get a reaction from the PCM.
Even though this is a Honda watch this video:
http://www.youtube.com/watch?v=za13UnpbH7E
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
(This post was edited by Discretesignals on Jul 13, 2013, 5:10 PM)
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jrhorton
Novice
Jul 13, 2013, 5:15 PM
Post #7 of 9
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Re: 2003 Lesabre won't start
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I will conduct the tests you show and report tomorrow afternoon. By the way, I discovered a nifty crank reference test at Easy Auto Diagnostics. dot com. A guy shows how to rig a test light with an led bulb on wire between two alligator clips. You hook it up at a particular ICM wire and the battery ground.
"When your assistant cranks the engine, the LED will stay lit continuously till the moment he lets go of the key and the engines starts to slow down to a stop. Only then will you be able to see the LED blinking ON and OFF. This is normal. You may have to repeat this step as many times as necessary to ensure you do see the LED blinking ON and OFF (when your assistant lets go of the Key)."
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Discretesignals
Ultimate Carjunky
/ Moderator
Jul 13, 2013, 5:23 PM
Post #8 of 9
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Re: 2003 Lesabre won't start
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If you have spark, you don't need to check for crank sensor signal to the ICM.
The ignition system on that vehicle will fire the coils even if the PCM is unplugged.
A crank sensor input problem won't cause loss of communications or no check engine light bulb checking.
The ICM sends low and high resolution crank position information along with cam sensor position information to the PCM. An LED bulb won't work with those circuits because they use 5 volt pull down circuits. If you have to check for CKP and CMP signals to the PCM from the ICM, you need a lab scope or graphing multimeter.
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
(This post was edited by Discretesignals on Jul 13, 2013, 5:25 PM)
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jrhorton
Novice
Jul 14, 2013, 2:17 PM
Post #9 of 9
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Re: 2003 Lesabre won't start
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1) Pin 16 (battery positive) shows 12 volts, the only one showing actual voltage;
2) Yes on 5 volts at the TPS gray wire;
3) Pin 16 shows 12 volts. Pin 2 (bus positive line) never stabilizes, but shows a fluctuating range from .2 to .7 volts; pin 4 (chassis ground) shows 6mv, pin 5 (signal ground) shows 16mv (there are no other other mating pin connections from connector to connector);
4) I don't know how to check the TPS signal for high voltage;
5) I don't own this equipment, and don't know how to do a bypass test with a test light.
Some other items I neglected to mention but might be relevant:
1) Prior to this problem, the battery was draining at night. I traced it to the power seat with an amp test and removed the fuse, so there is no more drain;
2) The idle air control valve continuously clicks, presumably open and closed, when the key is in the on position. This is my daughters car, and and she bought it 2 1/2 months ago. I am not sure when this particular problem began, but I think when the car first would not crank a few weeks ago.
3) When the key is in the on position, the running lights cannot be shut off by any switch or button. I've removed the daytime running light fuse and relay and the running lights stay on.
Thank you for your help. This is driving me bonkers!
(This post was edited by jrhorton on Jul 14, 2013, 2:56 PM)
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