Gauge cluster and odometer dead

[Guest Dive Dive]

Picked up my 07 Cayman after having a heater hose burst halfway between the engine and front and now the gauge cluster is dead.   The indicator lights above the gauges work but all the gauges and odometer are dead.   Could it be related to the burst hose somehow?   I’m not a believer in coincidence. 

[Chargerman]

Yes it could be related. If the hose burst in the bay where the processor is located it may have soaked it or when they snaked in the new hose they could have upset the wiring. The processor is located in the ceiling of one of the basement bays in my Coach

[DavidL]

Enjoy the free odometer miles 🙂

I assume the gauges work via CAN communications.  ie: digital signal.  only takes one break in the wire for all to go away.  When you turn ignition on...do the gauges make a full check sweep?  Did they ever?  That might give a clue if it's power or ground that is missing.

[Guest Dive Dive]

Update.  I pushed and moved every wire and fuse on all the various fuse boxes.  Now it appears to work all of the sudden. 

[Guest Dive Dive]

12 minutes ago, DavidL said:

Enjoy the free odometer miles 🙂

I assume the gauges work via CAN communications.  ie: digital signal.  only takes one break in the wire for all to go away.  When you turn ignition on...do the gauges make a full check sweep?  Did they ever?  That might give a clue if it's power or ground that is missing.

When I turn the ignition switch the gauges move a little then go to the readings that I think are correct.   When I start the engine all gauges zero and then sweep up to the same readings as before.   Of course the engine related gauges are zero until the engine starts.  

[DavidL]

17 minutes ago, Zigman64 said:

Update.  I pushed and moved every wire and fuse on all the various fuse boxes.  Now it appears to work all of the sudden. 

Well, I might have recommended to do a little, test, a little more, test again.  To isolate where the issue is (it's still there).

[Guest Dive Dive]

DavidL I’m sure you are absolutely correct.  It’s always disturbing when I don’t know the cause of an issue.   Question:  I presume that the diagnostic port gets information directly from the processor and takes the gauge cluster out of the loop.   Is that correct?

[DavidL]

7 minutes ago, Zigman64 said:

DavidL I’m sure you are absolutely correct.  It’s always disturbing when I don’t know the cause of an issue.   Question:  I presume that the diagnostic port gets information directly from the processor and takes the gauge cluster out of the loop.   Is that correct?

Yes, the diagnostic port is connected to the CAN network.  All of the CAN connected modules are accessible via the diagnostic port (typically engine ecu and transmission ecu and antilock brake module in an RV.  Cars have tons more).

You can check the diagnostic connector with an ohmeter.  Should have 120ohms resistance between CAN and ground.  Ideally you would have an oscilloscope to see the wave patterns.  Do you have a scan tool?  But generally, if it's running and driving, the CAN is working.  The gauges are likely fed off of a CAN module that then feeds the gauges.  If this module was offline, then engine would still start but gauges wouldn't read values.  I am thinking that's what might have happened to yours.  So, if that is true, then the loose wire would be near the instrument panel.  Did the heater hose get routed behind the dashboard?  Look for abraded wiring.

Edited April 6, 2021 by DavidL

[Gary 05 AMB DST]

What is CAN communication? 

Gary 05 AMB DST

[Guest Dive Dive]

33 minutes ago, DavidL said:

Yes, the diagnostic port is connected to the CAN network.  All of the CAN connected modules are accessible via the diagnostic port (typically engine ecu and transmission ecu and antilock brake module in an RV.  Cars have tons more).

You can check the diagnostic connector with an ohmeter.  Should have 120ohms resistance between CAN and ground.  Ideally you would have an oscilloscope to see the wave patterns.  Do you have a scan tool?  But generally, if it's running and driving, the CAN is working.  The gauges are likely fed off of a CAN module that then feeds the gauges.  If this module was offline, then engine would still start but gauges wouldn't read values.  I am thinking that's what might have happened to yours.  So, if that is true, then the loose wire would be near the instrument panel.  Did the heater hose get routed behind the dashboard?  Look for abraded wiring.

Thank you for the information.  I’ll check further.  As for the hose, they just ran the hose from the metal pipe back to the engine.   I still have to replace the portion that runs from the heater core to the front part of the metal pipe as well as all the other hoses on the coach while I’m at it

[Dennis H]

2 hours ago, Gary 05 AMB DST said:

What is CAN communication? 

Gary 05 AMB DST

Gary, it's actually CAN bus. Created by Bosch Electronics originally for Aerospace but now used in most vehicles. CAN stands for Controller Area Network. It's basically a central controller that monitors all of your vehicle's systems and routes the electronics accordingly. There's a more detailed and confusing description available but you get the gist......Dennis

[Dave P]

I am dealing with the exact same issue on my 2008 Camelot. I've had it at the shop and it starts working so the shop can never diagnose it. Please keep posting if you find the problem. Also, I had no previous repair when it started, the gauges just locked up and stopped moving. 

[Gary 05 AMB DST]

Thanks Dennis.

I know that my 05 HR Ambassador and other Monaco/HR from the early 2000's was before CAN bus. I remember on the assembly plant tour in Wakarusa, the wiring assembly area had a life size layout of the motorhome and the workers actually ran wire from the fuse box location to the item/items on the circuit. When everything was done, the wires were bundled and installed in the upper curb side ceiling/wall corner   (so they said) of the motorhome at assembly. I am so thankful that my 05 was   pre-CAN Bus and DEF. I can do wire not electronics.

Gary 05 AMB DST

[Guest Dive Dive]

I sure will Gary 05. Thanks to all for responding

[Gary 05 AMB DST]

Dennis, I'm more confused than before. I'm just going to continue thinking that I have wires not electronics, other than the ECM, Oh and the transmission, Oh and the anti-lock brakes. I have heard horror stories that just simple devices don't work.

Gary 05 AMB DST

[Dennis H]

Well the CAN bus is certainly a PITA sometimes. I've been playing with my Mercedes and the CAN doesn't like changing the radio head, it doesn't like LED lights and it gets really POd at me trying to change out the headlamps.....Dennis