I have a 2001 l200 and it is giving error code p0340, and now wont start. Its does roll over though. How do i repair this issue
Most of this came from TSB 98-T-49A, and a few of my tips thrown in.
Both P0340 and P0341 both relate to the Camshaft Position Sensor(I will
just call it Cam sensor from now on), the only problem is that the
S-Series engines don't have a Cam sensor, not a typical one at least.
instead, the DIS module watches when the #4 spark plug fires on the
compression cycle and fakes a Cam sensor signal from it. the tricky part
is that on a DIS waste spark system, spark plugs fire with their mated
cylinders(1/4 and 2/3 in 4 cylinder engines) every time the cylinder is
at TDC, regardless of weather the cylinder is on exhaust or compression.
However, it takes far more voltage to fire a spark plug on the
compression stroke then on the exhaust stroke, due to the compressed
air(more air molacules, more air the spark needs to jump, more
resistance to spark). The increased voltage needed on the compression
stroke is detected by the "#4 sensing circuit" inside the DIS module for
the Cam sensor signal. if the resistance of the secondary system is not
in the proper range or something else is affecting the voltage draw,
the "#4 sensing circuit" will be unable to work properly.
In short, anything worng with the ignition system, bad Cam sensor signal.
Next for the diagnositic, i'm converting this from a graphic map to a text format, so bear with me...
Step 1: remove secondary wires from spark plugs, keep the wires on the
coil. measure resistance from #1 wire to #4 wire and then #2 wire to #3
wire. resistance should be 11k ohms to 45k ohms(YIKES thats a wide
If resistance is in specs, go to step 2, if not in specs, go to step 3
Step 2: remove secondary wires from the coil packs. check for corrosion on the towers and wires.
If there is corrosion, go to step 4
If not, go to step 5
Step 3: remove secondary wires from the coil packs. check for corrosion on the towers and wires.
If there is corrosion, go to step 4
If not, go to step 6
Step 4: Replace or clean coils and/or wires as nessaciry. Retest to confirm.
Step 5: Remove spark plugs. Check for carbon or abnormal wear and proper gap(0.040 in)
If plugs check out good, go to step 8.
if the plugs are bad, replace as needed and retest to confirm.
Step 6: Measure resistance of individual secondary wires. specs are 1.5k
ohms to 15k ohms ( thats what this chart says, but my knowage says 8k
ohms is normal, greater then 12k ohms should be replaced)
If wires are in spec, go to step 7
If wires are bad, replace as needed and retest to confirm
Step 7: Measure resistance from tower to tower on the coil packs (hold tight for good reading). Spec is 8K to 15K.
If coils are in spec, go back up to step 5
If coils are bad, replace as needed and retest to confirm
Step 8:(90% of the time i bet the problem is solved by now) Start
engine. Perform underhood visual inspection of the ignition system,
check for arcing(best done in a dark area, if you are inside a garage,
besure the exhaust is vented). Wet DIS module, coils, and secondary
wires with salt water to provide optional ground path.(arcing from the
wire boot to the valve cover is possible, but would be hidden)
If arcing is present, replace wires or coils as needed and retest to confirm.
If not, go to step 9.
Step 9: Turn ignition off, backprobe J3D03 (Circuit 633, brn/wht wire)
at PCM with voltmeter. connect other lead to ground. Turn ignition on,
engine off. Measure voltage.
less then 4.5 volts, go to step 10
4.5-5.5 volts, go to step 12
more then 5.5 volts, go to step 11
Step 10. Check connections in circult 633, repair short to ground, retest to confirm
Step 11. Repair short to voltage in circuit 633, retest to confirm.
Step 12. Start engine, at idle observe voltmeter
less then 2.0 volts, replace DIS module, retest to confirm
2.0 - 4.0 volts, problem intermittent
4.0 - 5.5 volts, go to step 13
more then 5.5 volts, go back up to step 11
Step 13. Turn ignition off, backprobe circuit 633 at DIS module with voltmeter, other lead to ground. check voltage.
4.0 volts or less, repair open/high resistance in circuit 633, retest to confirm.
greater then 4.0 volts, go to step 14
Step 14: Inspect terminal on DIS module for looseness or poor connection.
If terminal is bad, repair it
If terminal is good, replace the DIS module.
thats all of the diagnoistic chart, anybody who has done this in the
past feel free to throw in your tips/opinons. I would like to add three
1. Check the grounding bolt on the DIS module for corrosion.
2. besure the secondary wires are fully seated, you should feel/hear a click
3. use dielectric grease on the coil towers
Dec 23, 2010 |
Saturn L-Series Cars & Trucks