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1994 Chrysler LHS cranks but won’t start

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Good evening, I have 1994 Chrysler LHS that is a crank but no start. I pulled into a parking spot and was sitting idle for a 3 minutes and the car shut off, never restarted, only cranked. Dealership specified the PCM wasn't sending correct voltage to the starter. I found a PCM and replace it myself (company said, plug and play type) - crank only, no start. I replaced the starter - crank, no start. Replace ld the battery - crank, no start. I didn't have a fuel pressure gauge but I used my key to press in the insert and fuel shot out, I'm assuming meaning that the fuel pump works. What is another step/steps I can take to diagnose the problem? Thank you for your time. 

Did you install the crank correctly

What is the crank? You mean the starter?

2 Answers
4

If the PCM wasn't sending the correct voltage to the starter, why did it crank?  Please see FAQ section.

Why the down vote @twobsolo? Based on the info you gave, it's a legitimate question.

I'm not even sure how I did that. I was pressing the arrows not knowing what they were

I know nothing about how the electrical part works or how to diagnose it. I don't know what the PCM is for completely. I just know 2 other shops couldn't diagnose the problem and the one dealership they said something about the PCM was going to charge me $1200 to change a part that I could do myself

4

What's confusing us is that you say the car will Crank but the dealer blamed the starter circuit.

If the vehicle cranks, there isn't a problem with the starter or the starter circuit.

You say the LHS will crank so let's assume that this is a Crank, No Start.

The 1st question to answer, "is the engine getting spark?"

Let's look at the ignition wiring diagram. I highlighted Red for Power and Green for Ground signals from the computer that fire the individual ignition coils. (it's a wasted spark ignition. 3 coils for 6 cylinders)

The 1st thing to notice is that the ignition coils get their Power from the ASD relay. ASD stands for Automatic Shutdown Relay and the computer controls it. (control side of the relay isn't shown in the diagram).

How it works is that the computer needs a signal that the engine is turning (from the crankshaft position sensor and camshaft position sensor) before it will energize that relay and provide Power to the ignition coils (and the fuel pump relay).

EXCEPT when you first turn the Key to ON.

When you first turn the Key to ON the computer energizes the ASD relay for a second or two to energize the Fuel Pump Relay and prime the fuel rail.

And you're saying that you stuck your key in the schrader valve on the fuel rail and gas shot out. That seems like the computer has control of the ASD relay (for at least the first second or two (like it should) when you turn the Key ON (When it isn't relying on crankshaft position sensor or the camshaft position sensor input voltages).

I'm going to post a link to a tutorial on how to start troubleshooting this from a website that assumes you know absolutely nothing about cars and walks you through it step by step.

But one thing. On Page 3, "Verifying Coil Pack Is Getting Power". 

I need you to perform one more test.

Let's look at that page here.

1st. For this test you don't have to leave the wiring connector connected to the coil pack like it says in Step 2.

You don't have to "backprobe" the connector by sticking a pin or something into the backside of the connector.

Just disconnect the connector from the coil pack and probe that number 3 socket terminal.(it's easier).

So the "one more test" I'd like you to do is after you check for Power from the ASD relay to the coil pack while cranking (step 6), is to turn the car OFF, then with your test light alligator clip still on the battery negative post, and the test light probe in the "number 3" wiring connector socket, have a helper turn the Key to ON. (not start, just on).

The test light should light up for a second or two and then go out. That will confirm that the computer has control of the ASD relay and the wiring between the computer and the ASD relay and the coil pack are good. 

AND IF you get power to the "number 3 terminal" for a second or two after Key ON,  but you aren't getting power to it while cranking we need to start looking into the Crankshaft position sensor circuit and the Camshaft position sensor circuit. 

Here's that link:

https://easyautodiagnostics.com/chrysler/3.3L-3.8L/coil-pack-tests-1

 

 

 

 

 

This post was modified 2 days ago by jack62

@jack62 to the rescue, again. Thanks.

Sir / ma'am this is amazing info. I'll have to take my time to understand/digest this. I'm diligent so I'll figure it out. Thank you very much.

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