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Jerry
Jerry, Master Mechanic
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1993 Buick LeSabre: 3.8...start problem...crank, but no start.

Resolved Question:

I am working on a 1993 Buick LeSabre 3.8. I have a no start problem. I have crank, but no start. I have fuel pressure, but no spark. I replaced the ignition module, and the crank sensor. I can''t find a diagnostic flow chart. please help.
Submitted: 9 years ago.
Category: Car
Expert:  Jerry replied 9 years ago.

Hi Jim, Super mechanic here. I have this diagnostic chart if it helps. You might have to make it bigger, Do you know if the cam sensor is working and are there any trouble codes?

 

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Home > Repair Info > Vehicle Repair Guides > ELECTRONIC IGNITION SYSTEMS
Diagnosis and TESTING
GM Bonneville/Eighty Eight/LeSabre 1986-1999
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Body & Trim Brakes Chassis Electrical Drive Train Driveability & Emissi . . . Engine & Engine Overh . . . Engine Electrical Fuel System General Information & . . . Suspension & Steering
Engine Electrical:
Electronic Ignition Systems
ELECTRONIC IGNITION SYSTEMS
General Information
Diagnosis and TESTING
Ignition Coil
Ignition Module
Crankshaft Position Sensor
Camshaft Position Sensor
Firing Orders
Charging System
Starting System
Sending Units
Specifications Charts


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COIL - IGNITION
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ELECTRONIC SPARK CONTROL MODULE
DISTRIBUTOR
DISTRIBUTOR CAP


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SERVICE PRECAUTIONS

See Figures 1 through 10

CAUTION
The ignition coil's secondary voltage output capabilities can exceed 40,000 volts. Avoid bodily contact with the C3I high voltage secondary components when the engine is running, or personal injury may result.

To avoid damage to the ECM/PCM or other ignition system components, do not use electrical test equipment such as a battery or AC-powered voltmeter, ohmmeter, etc., or any type of tester other than specified.

  1. Check for trouble codes, as described in Driveability & Emissions Controls . If any are found, refer to the appropriate diagnostic procedure in Driveability & Emission Controls.

  2. When performing electrical tests on the system, use a high impedance multimeter or quality digital voltmeter (DVM). Use of a 4 volt test light is not recommended.

  3. To prevent electrostatic discharge damage when working with the ECM, do not touch the connector pins or soldered components on the circuit board.

  4. When handling a PROM, CAL-PAK or MEM-CAL, do not touch the component leads. Also, do not remove the integrated circuit from the carrier.

  5. Never pierce a high tension lead or boot for any TESTING purpose; otherwise, future problems are guaranteed.

  6. Do not allow extension cords for power tools or droplights to lie on, near or across any vehicle electrical wiring.

  7. Leave new components and modules in the shipping package until ready to install them.

Click image to see an enlarged view
Fig. 1: Ignition system circuits - 3.8L (VIN C) engine


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Fig. 2: Ignition system diagnosis (1 of 2) - 3.8L (VIN C) engine


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Fig. 3: Ignition system diagnosis (2 of 2) - 3.8L (VIN C) engine


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Fig. 4: Ignition system circuits - 1992-93 3.8L (VIN L and 1) engines


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Fig. 5: Ignition system diagnosis (1 of 2) - 1992 vehicle with Type I ignition system


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Fig. 6: Ignition system diagnosis (2 of 2) - 1992 vehicle with Type I ignition system


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Fig. 7: Ignition system diagnosis (1 of 2) - 1992-93 vehicles with Type II ignition system


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Fig. 8: Ignition system diagnosis (2 of 2) - 1992-93 vehicles with Type II ignition system

Jerry and 5 other Car Specialists are ready to help you
Customer: replied 9 years ago.
I can't tell if the cam sensor is working or not. I have no trouble codes. Someone told me this problem could be related to the security coded key. In my experiences when the key or lock cylinder is bad the car won't even crank.
Expert:  Jerry replied 9 years ago.

Let's see..93, I think that is the "Pass key 2 " security. A diode in the key? They will normally turn off the fuel pump and injectors first. It seems that whatever system that you bypass, it will kill another.

With all that said, what I used to do was to first, check that there is power at the module. (pink I think) and then you can see if the crankshaft and camshaft sensors are signaling the module to spark. I am not sure of the wire color at the module but here is a diagram. You want to check the signal wire going to the module with red lead or low voltage test light.


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Customer: replied 9 years ago.
Something tells me that you think I'm dealing with a wireing problem, or a bad cam sensor. I have heard of a similar problem with a bad timing chain and tensioner. Have you ever experienced that?
Expert:  Jerry replied 9 years ago.

Oh yes Jim, I have, but I would think if it were a timing chain you would know by the way it cranks. Now I will say though, I have seen them where the little magnet comes off from the cam gear and then it won't sed a signal. (they warned us about that at the GM school), The truck is to try and isolate which sensor is not telling the module to or when to spark.

Also, on the crank sensor, were you able to get an even gap (.050) on each side of the trigger blades?

Customer: replied 9 years ago.
I didn't notice any adjustment on the crank sensor. Is their an easy way to test the cam sensor without removing it?
Expert:  Jerry replied 9 years ago.
Well, it is pretty much like the crank sensor. You want to check for a pulse with a low voltage 12v light or a red led light and see that it blinks. You can probe the brown and white wire (terminal A) to do this.