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This morning when I started my 2004 DHS, The idle was very rough. This is the first time that I have experienced any problems with the car.

Pulled the codes as follows;

P0300 current Engine misfire detected

P0202 current Injector control circuit.

U1016 history Loss of communication with PCM

The service engine light came on solid and began flashing at the approximate speed of 20 mph.

I don't want to drive the vehicle any farther than necessary because any un-burned fuel could affect the Catalytic converter.

I would like to check the spark plug & coil on cylinder #2, and look for a vaccuum leak, or EGR problem.

My question is how go you remove the engine cover. There is a latch in the back of the cover, but I can't seem to move or bend the cover far enough forward to clear the latch. I don't want to force or break anything so I thought it best to ask for assistance here.

Thanks in advance for your assistance...

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DTC P0201-P0208

Circuit Description

The control module enables the appropriate fuel injector pulse for each cylinder. Ignition voltage is supplied to the fuel injectors. The control module controls each fuel injector by grounding the control circuit via a solid state device called a driver. The control module monitors the status of each driver. If the control module detects an incorrect voltage for the commanded state of the driver, a fuel injector control DTC sets.

DTC Descriptors

This diagnostic procedure supports the following DTCs:

  • DTC P0201 Injector 1 Control Circuit
  • DTC P0202 Injector 2 Control Circuit
  • DTC P0203 Injector 3 Control Circuit
  • DTC P0204 Injector 4 Control Circuit
  • DTC P0205 Injector 5 Control Circuit
  • DTC P0206 Injector 6 Control Circuit
  • DTC P0207 Injector 7 Control Circuit
  • DTC P0208 Injector 8 Control Circuit

Conditions for Running the DTC

  • The engine is running.
  • The ignition voltage is between 11-16 volts.
  • DTCs P0201-P0208 run continuously once the above conditions have been met.

Conditions for Setting the DTC

  • The powertrain control module (PCM) detects an incorrect voltage on a fuel injector control circuit.
  • The condition exists for 5 seconds.

Action Taken When the DTC Sets

  • The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
  • The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

Conditions for Clearing the MIL/DTC

  • The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
  • A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
  • A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
  • Clear the MIL and the DTC with a scan tool.

Diagnostic Aids

  • Performing the Fuel Injector Coil test may help isolate an intermittent condition.

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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Your injector coils should have a resistance of 11 to 14 ohms

Fuel Injector Coil Test

Circuit Description

The control module enables the appropriate fuel injector pulse for each cylinder. Ignition voltage is supplied directly to the fuel injectors. The control module controls each fuel injector by grounding the control circuit via a solid state device called a drive. A fuel injector coil winding resistance that is too high or too low will affect engine dirveability. A fuel injector control circuit DTC may not set, but a misfire may be apparent. The fuel injector coil windings are affected by temperature. The resistance of the fuel injector coil windings will increase as the temperature of the fuel injector increases.

Diagnostic Aids

  • Monitoring the misfire current counters, or misfire graph, may help isolate the fuel injector that is causing the condition.
  • Operating the vehicle over a wide temperature range may help isolate the fuel injector that is causing the condition.
  • Perform the fuel injector coil test within the conditions of the customers concern. A fuel injector condition may only be apparent at a certain temperature, or under certain conditions.
  • If the fuel injector coil test does not isolate the condition perform the fuel injector balance test.

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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Fuel Injector Sight Shield Replacement

Removal

Lift at the front of the fuel injector sight shield (1) in order to disengage from the intake manifold ball studs (2).

Remove the sight shield (1) from the engine

Installation

Position the fuel injector sight shield (1) to the engine in the following order:

Insert the sight shield (1) under the secondary air injection (AIR) shut-off valve bracket. Align the sight shield (1) over the manifold ball studs (2).

Push the sight shield (1) down until fully engaged to the intake manifold ball studs (2).

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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BBF...

Thank you for the quick an very informative responses.

So, the decorative cover, on the top of the engine, is referred to as the fuel injector sight shield.

On my 93 Eldo, the top cover was held down by 4 bolts and quite easy to figure out the removal.

This is the first time the DHS has required any service other than routine maintenance, and I thought it better to ask first rather than break something.

Thanks again...

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No problem, let us know how this turns out. Try using a listening device next to #2 and see if its ticking, test its resistance and see if you can test the driver by checking the voltage firing it.

I am not sure if you can use a NOID light but check this

http://www.noidlight.com/

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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This morning I went out to measure the resistance of the fuel injectors and found that the front injector wire harness has had the majority of the insulation burned off all four injectors. The rear bank appears fine. My concern is that I can replace the harness, but don't want the new one to likewise have the same problem. I'm intending to perform a thorough inspection of the wire harness as it is removed to determine where the point of initial failure started. I'm intending to search the archive to find if anyone else has experienced a similar problem.

Edited by BSchlossmann
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Very odd, we have not heard that here in all my time here.

I don't believe there is any excessive heat in the area. Does it look like they shorted, overheated and then melted?

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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After performing a closer inspection of the wiring going to injector 2 it was shown to be the only pair of wires which had become burnt. It also did a little damage to other wires pairs inside the harness going to injectors 4 & 6, 8 was OK. The wiring to injector 2 was the longest wire in the harness. I could't figure out how to remove the connector from the injector and didn't want to break anything. I removed the burnt electrical tape on the wiring to injectors 2,4 & 6 and re-taped. One of the wires going to injector 2 was broken and had to be spliced. Started the car, cleared to codes, and appears to be back to normal. I don't consider this a proper repair, and will keep an eye on it until a new fuel rail injector harness can be installed. I tried to look up the part number at Rock Auto and GM parts direct without any success.

If someone can explain how to removed the connector on the injector it would be much appreciated.

I would like to measure the resistance of each injector.

I'm concerned about what caused this wire to burn up in the first place. There were no pinch points to be found anywhere along the path of how the cable harness was positioned. Right now I'm thinking that the injector is going bad and this caused the problem.

At this point I'm intending to use a probe to listen to the sound to each injector to determine if there is a difference sound being made by injector 2.

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Removal of Injector

Remove the fuel rail.

Remove the fuel injector (5) by pushing the locking tab on the fuel rail toward the center of the fuel rail.

Remove the fuel injector upper O-ring (6).

Remove the fuel injector lower O-ring (4).

Discard the injector O-ring seals

The fuel injector O-rings should always be replaced whenever the fuel injectors are serviced. Be sure to install the correct O-ring for the fuel injector. If the O-ring is not seated properly, a vacuum leak is possible and driveability complaints may occur

Installation

Lubricate the new upper (6) and lower (4) O-rings with clean engine oil.

Install the new upper and lower injector O-rings on the fuel injector.

Install the fuel injector on to the fuel rail.

Install the fuel rail.

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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Thanks for the information on the removal of the fuel rail / injectors.

The problem I'm still struggling with at the moment is how to remove the electrical connector on the fuel injector harness from the fuel injector. Does this require a special tool ?

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Oh sorry, this is all they say about removing the electrical connector

Disconnect the fuel injector electrical connectors (1) from each fuel injector (2).

Here is the photo, look closely there may be a slight catch that you can disengage with a pick

Injectorelectricalconnector.gif

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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This is a 2-Way F Metri-Pack 150 Series connector

Here is the connector end view

InjectorConnectorEndView.gif

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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These 64 year old eyes even with reading glasses, combined with difficult lighting have a hard time getting a good look a the harness connector. Now that the cars is somewhat fixed, Tomorrow I'm intending to move it into the bright sun light hoping to get a better look. I'm still planning to do the resistance check with a DVM and listen to each injector with a mechanic's stet-a-scope.

Thanks for all your help...

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I know the drawbacks of over 40 eyes at 56, if you get a chance, buy yourself one of those multi-LED flashlights, they are REALLY bright and help a lot

At least you narrowed down the problem maybe that injector lead chaffed and grounded out causing the melted insulation

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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I seem to have the same type of problem with my 2004 SRX. It has a V-6 and says the # 1 injector has a problem circuit. I replaced the injector and checked the wiring for burn marks, found no burnt wiring and still have the misfire. I also replaced the spark plugs while I had the air/intake off to access the fuel rail. Has anyone had a wiring problem within the loom and where might I start to look without having to remove all insulation from the wiring harness to try to locate a intermitent short. The weather is still cold here and any help to shorten the repair time would be great.

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The diagram you posted is indeed what the connector looks like. I tried squeezing and also tried separating the two tabs while pulling up on the connector without any success. I'm on my way out the door to take another shot at the connector. I do have one of those multi led flash lights, I'll give it a try. I was using one to those head ban flash lights with the older style bulb. It give me fairly good lighting, but as you stated the LED should work better.

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Did you find anything wrong with the injector that you replaced? You also stated that your wiring harness appeared to be in good shape, mine was not. If it's not the injector and it's not the harness, this leaves the device that control the injectors. Some some models I have read that it's located below the air box, and I think it's referred to as the PCM, could be wrong. My number 2 was at least fortunate to be in the front part on the engine and much easier to work with than the one in the rear.

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In the bright sun light I was able to get a better look an the connector on the injector. You had to compress the four prongs in the connector on the side. This allow the grey piece to be removed. Next, you had to push in on the black connector at the bottom while lifting off the connector. The resistance of the injector measured at 13 ohms. I performed a little more electrical taping near the base of the connector. Listened to all eight injectors and from a sound point of view they all sounded the same.

I stopped by the Cadillac dealer hoping to get a part number and price for a replacement harness but they were closed on Saturday.

The DHS seems to be running fine and I checked the wire harness several times after taking short trips to ensure there was no additional evidence of melting or burning of the injector wire harness. Lastly, re-installed the engine site injector cover.

My remaining concern is what caused the wires to burn in the first place. I'm suspecting a bad injector caused the wires to over heat, melt and cause a short. If the SES light comes back on, I will immediately pull codes and re-check the injector wire harness where the repair was performed.

Thanks to BBF, Alias Scotty, orginally Mike, for all his help. By performing this repair by myself saved an estimated $400.00 by not having to take it to the stealer-ship. My preference is not to let other people work on my vehicles.

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WOW, Bschlossmann, I did not know you knew my alias, Scotty.... I am impressed.

I was thinking about your situation today as I was out and about.. Did you notice any sharp edges where the injector wire could have grounded?

I believe that if your injector itself shorted they would not have healed themselves, you would have gotten a bad resistence reading

Good diagnosis, if the harness is too much consider a scrap yard for the harness. Keep an eye on it, Scotty tongue.gif

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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