No Power to Instrument Cluster

jdgrand

2006 Dodge 2500 RV
I resolved an issue of no fog lights by changing the 70 Amp fuse on the power distribution off the battery positive terminal.

Now I have a new, worse problem. I have no power to the Instrument Cluster. Fuses to Cluster on Blocks 1 and 2 are OK. Lights work, engine will start, SRS light comes on in the Cluster. High Beam indicator comes on. But all other lights do not come on. Tachometer is not working, fuel gauge shows under 1/2 tank with and without power on. No odometer, no clock, no illumination.

License plate lights are working fine.

I did disconnect the parking brake indicator a while back, taped over the connector then. But when I just checked it I see that it has come off.

As I mentioned in my previous post the fuel gauge was acting strangely the last few times I drove the van. After running about 10 minutes the needle would begin bouncing from full to empty and the warning light would illuminate.

I read another thread that mentioned a fuel level sender issue that fried an Instrument Cluster. Hopefully that is not my problem.

Not sure if I did something while fixing the first problem (wouldn't be the first time) but I would appreciate your suggestions for further trouble shooting.

Thanks,

Jim
 

NelsonSprinter

Former Nelson BC Sprinter
I'm hoping you disconnected the neg cable from the battery during fuse fix at battery.
I'd look under seat for blown fuses, and check that all cables are plugged into ECU.
 

jdgrand

2006 Dodge 2500 RV
Yes, I did disconnect negative battery terminal before doing the other work.

I checked the relevant fuses in block 2 under the drivers seat -- are there others under there in another location?
 

Nautamaran

2004 140” HRC 2500 (Crewed)
Not sure of fuses, or of internal wiring, but the IC has both a fused Bat(+) (C2 pin 3, fed by 7.5 amp fuse under seat, also feeds Data Link Connector obdii pin 16) and a fused RUN-START (C2 pin 10, fuse 18) power pin. Most indicator lamps are lit by grounding through the sensor switch, so if a lamp is coming on, you have power on one of these feeds.
C2 is on the back of the IC, where you can confirm these power signals are reaching the cluster.
Section 8W of the service manual shows these connector pinouts.

-dave
 
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Eric Experience

Well-known member
JIm.
Fuses have a very important role. When they blow it is important to find out why, you do not mention what caused the 70 amp to blow, that is a significant fuse, you should examine your wiring loom in great detail, look very carefully where the loom passes through a hole or is supported by a bracket, the fuel gauge is behaving like it has a wire pinched under the tank. multiple problems are often an indication of a loom damage of some kind. Eric.
 

jdgrand

2006 Dodge 2500 RV
I will check the wiring loom for kinks, etc. and then I guess the next step is to check connections/wiring at the IC.

The bouncing fuel gauge and now dead IC may have nothing to do with the fog light issue.

The 70amp fuse I changed serves 'optional equipment' and apparently does not serve anything in the IC -- it was not blown but did look corroded and although its continuity tested OK replacing it coincided with bringing back the fog lights which are on the 'optional equipment circuit.'

Thanks for your suggestions!

Jim
 

220629

Well-known member
...

The bouncing fuel gauge and now dead IC may have nothing to do with the fog light issue.

...
Assuming those symptoms are related, I'd be looking at ground connection, connector connection, and harness issues in that order. With a bad ground other components looking for a power path could easily cause the fuel gauge to jump around.

There are ground lists in the Service manual 8W section schematics.

:2cents: vic
 

BrennWagon

He’s just this guy, you know?
Second on ensuring a solid clean ground as the best starting point. Ground failures seem to be more common in the winter and can give intermittent weirdness as the contacts fail.
 

Nautamaran

2004 140” HRC 2500 (Crewed)
The Instrument cluster power goes directly to ground G200 (firewall behind the battery), which is a relatively easy one to open and clean.

(fwiw: the fuel level sensor is a closed variable resistor, so would not provide a secondary path to ground)

Happy New Year,

-dave
 

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jdgrand

2006 Dodge 2500 RV
Thanks for the suggestions. I have cleaned the G200 Ground on firewall by the negative battery post -- didn't look bad. But battery was dead so I couldn't check if that ground was the problem.

I have pulled battery to charge and clean up battery tray. Can move on with checking tomorrow.
 

220629

Well-known member
Added.

...

I checked the relevant fuses in block 2 under the drivers seat --
...
I would not trust the fuse map listings. They are notoriously incomplete.

Before going much further I would carefully check each and every fuse both under the steering column and under the driver seat.

:2cents: vic
 

jdgrand

2006 Dodge 2500 RV
Thanks for the suggestion Vic. I checked them all, including three unlisted (horizontal) ones in Block 2 under driver's seat. All look and test OK. I haven't finished cleaning up and repainting the battery tray but should be able to complete that tomorrow and reconnect battery for further tests.

Jim
 

autostaretx

Erratic Member
Here's my fuse panel ... i'm pretty sure the horizontal group is/are standard across US T1N Sprinters:



--dick
 

jdgrand

2006 Dodge 2500 RV
UPDATE

After checking/cleaning ground connection and ALL fuses I reconnected the battery and symptoms persist.

I noticed that the fuel gauge reads 1/2 tank whether there is power on or not, even with battery disconnected. I would expect it the read Empty with no power so I fear the cluster may be fried.

I have since opened up the dash to check connectors on the Instrument Cluster. They were on tight. I found two interesting things while doing that.
1) This is a replacement cluster (manufactured in 2016)(see photo)
2) The fuel level sensor wires were taped together with vinyl electrical tape (not the same type used elsewhere to wrap harnesses)(see photo).

This leads me to believe that the fuel level sensor may have caused problems in the past and perhaps fried the original cluster.

I think my next steps should include (not sure the order is the most logical):
1) test continuity of ground wire from IC -- not sure how to do that though.
2) test fuel level sensor circuit -- again not sure how.
3) test fuel level sensor itself which I think requires dropping the fuel tank.
4) check wiring from IC to fuel sensor


I welcome your thoughts.

Thanks in advance,
Jim
 

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Nautamaran

2004 140” HRC 2500 (Crewed)
The fuel level sensor is a simple two wire loop out to a variable resistor located in the tank module.
The IC reads the resistance across the two wires then sets the dial pin’s servo motor.

I have a spare instrument cluster and skreem on my work bench, and power the IC up regularly by connecting its ground (C2 pin 6), B(+)(pin 3), then Fused Run/Start (pin 10) to a battery. The indicator lights will cycle as if you turned the key, them after several minutes the fuel gauge begins cycling from Full to Empty. Connecting a fixed resistor across the two fuel sensor pins will cause the gauge to snap to the associated setting. A 170 ohm resistance across C1 (black) pins 1 & 10 should move the needle to about 1/2 full.

You can unplug the cluster from the black and white plugs and probe the pins/holes directly. I use a ribbon connector from an old floppy drive on the cluster-side connectors and breadboard leads on the van’s harness.

Pinouts for the two plugs are given in section 8W of the service manual.

-dave
 

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jdgrand

2006 Dodge 2500 RV
Dave,
What would cause the fuel gauge dial servo motor have the pin be stuck at 1/2 a tank?
A short in the fuel level sensor or its wire loop?
 

Nautamaran

2004 140” HRC 2500 (Crewed)
:idunno:
The IC is an electro-mechanical device... it could be a partial short in the sensor loop, a fault in the stepper motor, or something burned out on the circuit board. As Vic suggests, I’d start with a visual inspection under that tape, then take an ohm meter to the connector and check the loop resistance, and confirm the voltage at the power pins with a test lamp or other small load. (You would need to drop the tank to check the other end... not sure that’s justified yet without a known-good cluster)

I would then feed 12 volts to the cluster. The plastic housing can be unclipped and the board inspected. Some here have found and repaired burned traces.

-dave
 

jdgrand

2006 Dodge 2500 RV
Vic,
I did check under the tape. Wires were unscathed so I presume the tape was used to identify them at some point.

Dave,
Thanks for the suggestions. I hope to have time to do those things today.


Jim
 

koenb

Active member
Firstly, I would suggest a read through of the Description and Operation section of the instrument cluster at the beginning of section 8J in the service manual. For me, these sections always help come up with potential ideas to test to aid troubleshooting and help narrow down and isolate the issues.

After reading through this thread and your described symptoms, I would first try to eliminate the fuel sender and associated wiring from the equation and then go from there. As previously mentioned, its a simple variable resistor type sender, a float in the tank changes resistance. As Dave mentioned, read ohms across pins 1 and 10 of plug C1 ref. diagram 8W-30-3. How much fuel is in the tank? Apparently 170ohms is roughly half a tank. The operation section of the fuel gauge says as fuel level decrease, resistance would increase, so if you have less than half a tank, you would see higher than 170ohms, and vice versa. I would also try rocking the van with your ohmmeter connected across pin 1 and 10, you should see a fluctuating value as the float moves from sloshing. Maybe someone else could chime in here, but I would assume there is a plug connector at the sender? If you unplugged the sender, creating an open, the fuel gauge should default to empty and the low fuel light should stay off ref. fuel gauge description operation section 8J-18. Check if the gauge needle is still stuck at ~half tank with sender unplugged.

In addition, with long test leads, you can test continuity of the two wires going from plug C1 (black) at the IC, to the plug at the fuel sender. But before you measure the ohmic value of the wires, test and record the resistance of your test leads and subtract that value from what you are reading on the van. Should be pin 10 to the Black/Blue wire and pin 1 to the brown wire at the sender. Low ohms <1 is what you want. Next would be test the two wires for shorts to ground. Then shorts to each other, while checking this, wiggle the wires near the plugs to make sure. Then, with only the battery negative cable connected and for safety put a rag over the positive terminal to ensure the positive lead doesn't contact accidentally, test continuity from the brown wire at the fuel sender plug to battery negative. If you did not get continuity to ground through the brown wire, it may go through the circuit board of the IC and find ground out through pin 6 on C2, make the check again from the brown wire at the sender with both C1 and C2 plugged in (if previously unplugged). While you're checking grounds, verify low ohms from pin 6 on plug C2 unplugged (white plug) to battery negative post. The other thing to check with the fuel sender unplugged (battery connected) would be 12V on the black/blue wire at the sender at each key position. As I understand it, should have no voltage at key off, and voltage at ignition on and while running. Please correct me if I'm wrong.

I might be forgetting or overlooking some things, but in theory this should make all the checks needed to eliminate the fuel sender and circuit. As mentioned in the description section 8J, there could be CAN BUS issues going on here that would require dealer level diagnostic scanners to troubleshoot the IC further.

Hope this helps your troubleshooting.
Koen
 

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