Fuel injector wiring diagram needed

Hello,

Please check out the diagrams (below). There are three pages, each split into two images for better resolution (example page 1A and page 1B).

Here's a repair guide containing OBD II trouble code definitions:

https://www.2carpros.com/trouble_codes/obd2

You may also want to take a look at these repair guides discussing fuel injection systems:

https://www.2carpros.com/articles/how-fuel-injection-systems-work

https://www.2carpros.com/articles/how-to-test-a-fuel-injector

If there's anything else we can help with, please let us know.

Thanks! Wendy W.

Thanks Wendy, I have an ICarsoft form MB. I want to check the ohms on injector wiring to the ECU but don't have a wiring diagram until now. I really appreciate your prompt answer...Ron

You're welcome! If you need anything further, please let us know!

Thanks! Wendy W.

Wendy, I finally matched the pins and performed an OHM continuity test and all six injector wires to the ECU work. I do have a problem with P0202. The car can be driven around the block but has major hesitation. Because there is continuity, does that mean that the ECU is bad? I am attaching an image of my findings and hope that they may be useful to others.

Hello Ron,

Thanks so much for the update!

Do you happen to have any freeze frame data from your scanner from when the P0202 code was set?

The P0202 code can indicate faulty injector wiring, but it may also point to a faulty injector. Have you been able to test the cylinder 2 injector? There could be an open or short circuit within the injector.

Have you been able to measure the resistance across the injector itself? It looks like the resistance should be between 14 and 18 ohms on this vehicle.

If you haven't already, you may also want to check all the fuses.

I've attached photos (below) to show the location of the cylinder 2 injector in case you needed that.

Thanks, Wendy W.

Wendy, I will check the OHM resistance on injector 2. Is there a fuse diagram that shows which fuse affects cylinder 2?
Thanks, Ron

Hi Ron,

The injector fuse should be fuse 57 (25 amp - marked with a red box on the photo below) in the left rear engine compartment. It wouldn't hurt to do a quick check on all of the fuses, though. I'll be curious to hear what the resistance check on the injector reveals.

Thanks, Wendy

Hi Wendy,

Your curiosity was an educational concern. Injector 2 did not pass the continuity test. The other injectors averaged 15. I installed another injector that averaged 16. You were "right-on"!
Last summer I was getting a 0600 code and the clock would start turning in one direction and then the other but would stop after about five minutes. Then weeks later the clock would turn, and the headlights would go on and off and the turn signals would not work. until about 5 minutes and all would normalize.
I chose to be proactive and decided to change the spark plugs and the injectors.
All worked well for about a week, then I started getting error 0202 along with the 0600. I communicated with an online mechanic. (I'll reveal that later if necessary)
He said check the continuity of #2 injector with the plug on the ECU. It checks out good. He said that it was the ECU. I sent the ECU for repair, and they said that it did not exhibit any problems and sent it back.
I have an ICarsoft II for Mercedes. The 0202 error code is gone but a 0201 remains. It passed the continuity test and the injector had 15. I connected a NOID light that did not light up. I inspected all of the fuses under the hood.
The different errors oftentimes mention "instrument cluster". I can get a used instrument cluster.
Is there a common link with the instrument panel and the error code for #1?
I can send a .pdf of the last test. How should I send it?
I'm not a mechanic but have had multiple cars I've worked on. Mostly Mercedes both gas, diesel and diesel truck.
Electronics are not my forte. I wish I still had my TR3 that was stolen. No computerization and I could hand-crank it if the battery was dead.
Thanks for any suggestions you may have.
This will be a case for journaling.

Wendy, this afternoon I was reviewing the results of the test I did today. On manual select there are 47 potential tests in automatic there are 27.
About halfway through the recording process all of the lights and gauges on the instrument cluster lit or showed temperature/gas level. So, the lights and gauges may be good, but something is missing. Could that be low voltage? If so, would that be the regulator?

Thanks again for your valuable input. Ron

Good evening!

It sounds like you've found a lot of good clues in your diagnostic process! I'm glad you were able to check the injector as well.

Have you been able to do a check of the charging system? Here's a repair guide that might help:

https://www.2carpros.com/articles/how-to-check-a-car-alternator

In the meantime, I'll do some more research and see what else I can find for you.

Thanks, Wendy

Hi Ron,

I did a little more research and found that there was a TSB concerning the instrument cluster. I've attached it for your reference. I've also included the schematic for the instrument cluster.

In addition to checking the charging system for proper DC voltage and checking to see if there are any AC voltage spikes, you may want to check the grounding points shown below. Even a little bit of resistance can cause some strange behavior with vehicle electronics.

I hope this helps,
Wendy

Wendy, I checked both the driver side and passenger side grounding wires. The passenger side was clean however, the driver side ground did need cleaning. I've attached pictures of both.
Afterwards I ran the car around the area for about 15 minutes and did not notice any difference in the clusters display.
Thanks, Ron

Hi Ron,

Thanks for the photos! I'm glad you were able to find the grounding points.

The code P0600 points to a CAN bus communication error of some sort.

I noticed that this vehicle seemed to be part of a software coding error recall. Do you know if this vehicle was repaired under the recall? There should be a sticker under the hood that shows if the repairs were completed. I've attached photos for your reference.

Another thing that sometimes happens is that the insulation on the wiring in the engine compartment starts to degrade and will even crumble off the wires, leaving multiple wires in direct contact. Have you looked inside the wire looms to check on the condition of the wiring harness insulation? This could lead to a CAN bus communication error as well.

Were you able to check the charging system?

Thanks, Wendy

Hi Wendy,
I haven't been able to check the charging system yet.
Here are the results of the latest test.
Hope this helps.
Thanks, Ron

Wendy,
Since I'm a one-man operator, I may drive to AutoZone and have them perform a load test. With only 5 cylinders firing it's more difficult to keep the RPMs up.
Thanks, Ron

Hi Ron,

Thanks for uploading the results of your diagnostic test. I see at least two references to undervoltage. That can cause communication errors in the CAN system and all sorts of drivability issues. Please let me know how the charging system check goes.

Thanks, Wendy

Hi Wendy,

I took the car to AutoZone yesterday and the primary battery was good but at 44%. The alternator showed as operational. I showed them the clock, front lights and lack of lights and instruments working on the instrument cluster.

Based on the tests and that the regulator is part of the alternator, they said that they believe that a new alternator is needed.

I called a company that repairs instrument clusters and they said "purchase a used cluster and if it works, send both the old and the new used one to them and we'll upgrade the used so that the mileage etc. is correct". He also said it appears that the main cause is affected by "under voltage".

So, I ordered a new alternator and will install it next week.
I'm adding two videos. One of the lights and the second one is the clock.

Thanks, Ron

Hi Wendy,

While I'm waiting on my alternator, I wanted to give you feedback on two of your comments:
1. I did a VIN search for Mercedes recalls and the only one for my vehicle pertained to the sunroof.
2. You made mention of potential wiring problems. Since my other MB is out of commission, I have resurrected my 1998 E320 wagon with 332,000 miles on its odometer. I had to replace a headlight bulb and the picture shows what you were talking about.

Thanks again, Ron

Hi Ron,

Thank you very much for uploading the photo, videos, and results of your research. Yes, that headlight wiring issue is very common!

I hope you're able to resolve the issue with your E320 clock running backward and the headlights turning off and on.

I've attached the replacement procedure for the alternator, belt, and instrument cluster in case you might need it.

In my experience, Mercedes vehicles can be a little particular when it comes to aftermarket alternators. I've attached the OEM part numbers for the alternator and regulator, just in case.

Thanks so much for keeping us posted! Wendy W.

Hello Wendy, I installed a new alternator and have attached the ICarsoft test results.
The low voltage error does not show up until the door tests.
I performed tests on the #1 injector and the results are on the attachment.
Prior to changing the alternator, I took the instrument cluster out and did a minor visual inspection and could not see any hot points. None of the lights or gauges worked. The only movement was the “possessed” clock.
Now, for no specific reason the clock has stopped winding and stops at the correct time, then the fuel gauge, engine temperature gauge, lighting and warnings all work…including the “Check engine” light!
When I turned the ignition off by backing it one click, let it rest and then started the car, the cluster would work.
What do you suggest the next action should be?
Thanks for your input, Ron

Hi Ron,

Thanks so much for bringing us up to date! I'm glad the instrument cluster seems to be behaving a little better now.

Looking over your scanner results, it seems like there's still a CAN communication error of some sort.

It looks like there are a couple of CAN connectors in the left front doorsill. I wonder if moisture has gotten in there and caused some possible corrosion? I know you've checked the grounds nearby those locations, but it might be worth it to take a quick look at these connectors as well. I've attached photos below of the connector locations.

Are there any aftermarket electrical parts installed on the vehicle? I've seen an aftermarket replacement taillight that caused drivability issues and caused the vehicle to drop into "limp mode". The aftermarket taillight was interfering with the CAN communication somehow and once we installed an OEM taillight the issues cleared up immediately.

Is the battery testing out good now that you have the charging system back up and running?

Thanks, Wendy W.

Wendy,

If you look at the ground terminals, the one on the driver's side is not as clean as the passengers. I will check the connections. FYI, removing the carpeted floorboard on the driver's side requires patience and strength.
Would the CAN problems cause a 0201 or misfire in cylinder 1. The wiring checks out as good.
Thanks again,

Ron Chaves

Hi Ron,

If the CAN system is experiencing communication errors, it could cause the signal to activate the injector to be blocked.

Have you tried clearing all the codes since you've installed the new alternator?

Thanks, Wendy W.

Hello once again,

I cleared the codes and the previous email shows the fault codes after changing the alternator. One major difference is that "low voltage supply" only shows in two places.

This afternoon I began looking at the CAN connections that you so kindly shared.
I've attached images of what I've seen so far.
The picture with the green wires, are connections I've cleaned with electrical contact cleaner. That CAN is X30/5.
CAN X30/7 shows green corrosion.
Do you have the wiring diagram of X30/5 and how to disconnect the connections? I am fearful of breaking a connection. Are there any instructions or videos on how to clean the connectors?

Thanks,
Ron

Good evening, Ron,

Thank you very much for attaching the fault codes from your earlier test. I did look through them carefully, which is what made me wonder whether there could be an issue within the CAN system since there were codes for several different components. I just wanted to verify that these were "fresh" codes since the alternator replacement. Thanks for clarifying that for me.

I've attached schematics for the CAN system wiring in the door sill area.

I'll try to find an answer for you regarding how to disengage the connectors, but at first glance, it seems like the tab I circled in red may need to be pushed either up or down with a small pick. I haven't verified this yet, so please use care if you decide to try this.

Also, it's always a good idea to make sure the battery is disconnected when working on any part of the electrical system. The CAN system is especially sensitive to electrostatic discharge.

I'll keep working on trying to get you some more information, but I wanted to share what I could for now.

Thanks, Wendy W.

Wendy,

I may have created a problem as I disconnected, cleaned and re-connected the green wires in section X30/7 without disconnecting the battery.

The battery is disconnected and I'm working on X30/5, which is the CAN closest to the kick pad or front.

I disconnected two of the eight and that's where I saw corrosion. The problem is that I can't get them back on and I cracked part of the plastic on one.

There has to be a secret to working with or cleaning the connectors. I thought that instead of disconnecting the remaining five I'd just flood the connectors with electronic cleaner and wiggle them when I did. But now I can't get the two that are off back on!

Thanks so much for your input.

Ron

Wendy,
I was down on my knees with lights, my iPhone, even a Nikon trying to take pictures and make sense of what I was looking at.
Finally, I had an AHA moment as I researched the definition of a BUS and began looking for pictures. I realized that the strip was the bus and that the bus could be detached, making it easier to take pictures.
So, I was able to disconnect the bus from the side and took pictures. I saw the telltale sign of corrosion in the form of green specks under the bus.
I still don't know how to disconnect the connector from the bus. Perhaps I need to spend some time praying while on my knees!
Attached are pictures of the bus from the internet and from pictures I took.

Thanks,
Ron

Hello!

Thank you so much for sending all the photos, they were very helpful!

The plastic piece that broke appears to be a Tyco socket housing, which can be found online. If you enter the part number "0305452828" and "Mercedes" in an online search engine you should be able to find it for sale for less than $10.

Then if you search for "remove Tyco pins" on YouTube, there are a few videos that show how to lift the release tab and slide out the terminals so you can reinstall them in the new socket housing. You'll likely need a small pick or automotive terminal tool, which can be found in auto parts stores or online relatively inexpensively.

To remove the smaller socket housings from the larger cable shoe (part number 0025467940) it seems like you'll need to first release the two tabs on each end with a small flat-blade screwdriver (indicated with the red arrows in the picture below). Then carefully slide the cover off by inserting the screwdriver in the area marked with green highlighting. Once the cover is off, each socket housing should be able to come out individually.

Please let me know how it goes.

Thanks, Wendy W.

Wendy,

I am successfully taking the bus apart. There is corrosion.

However, I have another question that came up after I made a dumb move.
I closed the trunk lid... after the battery was disconnected. The key has been lost.
Is there anywhere that I can connect 12 volts or a point of + and supply power to open the trunk?
If need be, I can take the back seat out and cut a hole to access the locking mechanism.
From a dummy,
Thanks

Wendy,

My jumper cables were in another car, but I had another 12-v battery and connected a charger to the terminals. Then I used my alligator clips and put one to ground and one to the terminal with the fuses. The terminal in back. After a few minutes everything woke up and I opened the trunk.
From a Smarty,
Thanks for reading.

Hello!

I'm glad you were able to find a way to open the trunk and that you're having success with the CAN bus connectors as well. Please keep us posted!

Thanks, Wendy W.

Wendy,

The test often refers to CAN problems with A1. In researching it appears the A1 is on CAN X30/6. If that is correct, where is the CAN located? I saw pictures of its location on a 2002 but not a 2004. I looks like it's located above the brake pedal.

Thanks,
Ron

Hi Ron,

It looks like the X30/6 connector (cockpit voltage distributor) is located in the right front footwell. I've attached photos to show the location.

Thanks for keeping us updated! Wendy W.

Hello again Ron,

I've attached a diagram that shows the basic bus structure for this vehicle, along with the schematics for the X30/6 circuits.

I noticed that the right voltage distributor circuit (X30/4) communicates with the instrument cluster so I've also attached that schematic, along with the location of the X30/4 connector in case you wanted to check that as well.

I wouldn't necessarily expect to see much corrosion at the X30/4 connector because it isn't in the door sill area like the other circuits where you've been noticing the corrosion. It's possible that the connector has come loose somehow. It may be worth a look.

I hope this additional information helps.

Thanks, Wendy W.