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Discussion Starter · #1 ·
Hello,

I have a 04 Monte Carlo that will not start. I've tested fuel pressure so its getting fuel just no spark. I believe it might be my EOP. I checked the voltage to the Oil Pressure Sensor from the plug and PCM. It's showing about 9 Volts DC. Is this normal voltage?

I've checked the wiring harness for breaks and I have checked continuity on the 2 prong connector and the PCM. I have continuity on the power side and the ground that connects to the transaxle stud. I've ran out of things to check. I'm starting to believe I might have a bad PCM.

I would like to verify somethings with the 3800 experts.

Will the Engine Oil Pressure Switch stop the engine from starting? Its reading low in engine data2 from a tech2.

What voltage should i be seeing coming from the PCM to the EOP? I'd assume it should be 12 VDC.

Has anyone ever seen a pcm stop pushing enough voltage to properly run the Oil Pressure Switch.

I'd appreciate any help I can get. A PCM is quite expensive and I've already shot the parts cannon a few times already. :)

Thanks in advance for the help.

Best,

Roddergreg.
 

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Can you pull trouble codes ?

Use say there is fuel, but are the injectors firing?

If there is no spark, the crank and or cam signal may be absent, and might trip a code during cranking.
It could also be a dead ignition module but you need a scan tool first.
 

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Discussion Starter · #3 ·
Can you pull trouble codes ?

Use say there is fuel, but are the injectors firing?

If there is no spark, the crank and or cam signal may be absent, and might trip a code during cranking.
It could also be a dead ignition module but you need a scan tool first.
Can you pull trouble codes ?

Use say there is fuel, but are the injectors firing?

If there is no spark, the crank and or cam signal may be absent, and might trip a code during cranking.
It could also be a dead ignition module but you need a scan tool first.

I've pulled the trouble codes and I'm geting a P0520 Engine Oil Pressure Sensor/Switch Circuit Malfunction
 

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Did you swap a new oil pressure sender in, yet? It's a $7.50 - $12.00 part on RockAuto, even for the ACDelco part. Didn't see you mention that, yet, is all.
 

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Discussion Starter · #6 ·
I found this.
Try replacing that switch

Thanks dez and DB I appreciate the responses. I have replaced the Engine Oil Pressure switch. I replaced it twice. I bought a Standard at O'reillys but after reading bad reviews on that one. I purchased the AC/Delco Engine Oil Pressure switch. I don't think I'm getting enough voltage to the switch. Could someone test voltage on their 3800 on the power side of the connector and let me know what they are getting. When I disconnect the plug from the EOP and test the positive side I'm only seeing 9.3 Volts. I believe this should be 12 Volts.

Thanks everyone!

Rodder
 

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It'd need to be a Chevy with the gauge, not just a low pressure switch that Pontiac/Buick/etc. typically have. The service manual should have good info on this, if you seek that out (my old downloaded one is a spaz on Win10, or I'd have already answered this).
 

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Discussion Starter · #8 ·
It'd need to be a Chevy with the gauge, not just a low pressure switch that Pontiac/Buick/etc. typically have. The service manual should have good info on this, if you seek that out (my old downloaded one is a spaz on Win10, or I'd have already answered this).
I've checked Chiltons, AllData DIY and Mitchells. No resources include this information.. There are two wires that connect to the EOP A Black and a Tan/BLK. Seems like a simple circuit to me. The Tan/BLK is coming from Pin 19 which is the Oil Pressure Switch. Circuit 231. I'm going to attach the wiring schematic here. Should I have 12+ VDC at the signal wire from the pcm?
\\
 

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Discussion Starter · #9 ·
So I tried a few things. I replaced the crank position sensor. After replacing the sensor the car had spark and started and ran for about 15 minutes. After that time it died and will not start. Any ideas what my issue could be?

Thanks!
 

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Discussion Starter · #10 ·
Turns out it was an issue with my ICM. When I backprobed the 12V power on the connector. The car started without issue. I remove the connector and somehow antifreeze had pooled up in the connector. There was atleast 2-4 ounces inside it. Cleaning out the plug, spraying on some wire dryer on it fixed the issue. Thanks everyone for their help. Who would have thought an oil pressure switch circuit error would be caused by water inside the ICM connector?

roddergreg
 

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Awesome. Be sure to put some dielectric grease in there when you get a chance. Water tends to get around the engine bay, especially driving or parked in rain. Spark plug wire connections, battery terminals, and harness ends all benefit from the extra help that grease provides.
 
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