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Replacement head unit issue


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#1 n13ldo

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Posted 05 December 2017 - 09:38 AM

Hi Guys/Girls,

 

I bought one of these all-in-one head units from Aliexpress, see photo below. 

 

1. It didn't power up (resolved after a circuit board disassembly/reassembly presuming internal ribbon cables loose)

2. The lower mounting tabs where incorrect spacing (resolved after I drew and 3D printed replacements).

 

So the problem is that while all the controls for the HVAC work, the outside temperature isn't routed through to the dashboard lcd. In this photo the HVAC connector wasn't connected so the dash is showing the last known temperature from the factory head unit. When this new head unit is connected the outside temperature is given as 28c... for Scotland I don't think so. The push on the trip button only allows +-3 degrees either way of the current value.

 

I've studied the wiring diagram in the US PDF version of the service manual and can see the input signal from the sensor (pin 12, pink wire) - but can't work out where this signal comes back out to then go off to the dashboard to show the correct outside temperature. The chinese seller is useless in helping with this - they insist everything works with the 2003 Accord. 

 

I asked about on the XDA forums but as the HVAC module has nothing to do with the MTCD (Rockchip PX3) unit I've had no luck there.

 

Anyone been down this road before me? Any help would be gratefully received.

 

The weird band on the screen is just the shipping screen protector. Screen was perfect underneath.

 

 

20171004_170809s.jpg


Edited by n13ldo, 05 December 2017 - 09:39 AM.


#2 Channel Hopper

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Posted 06 December 2017 - 04:29 PM

You mention the US pdf, but has the supplier confirmed the screen is compatible with the European Accord of that era ?



#3 n13ldo

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Posted 07 December 2017 - 09:44 AM

The supplier didn't specify US or Euro Accord. However, the US PDF wiring diagram in respect of HVAC and the head unit matches my UK Accord. 

 

I was hoping someone on here would know how the value (a resistance value) from the temperature sensor behind the front grill ends up as a Celsius value on the LCD dash. 

 

Some interesting info on here: http://www.brisdance.../Electrics.html - I had discussions with this guy back in 2014 when I was thinking about a custom unit. Did contact him a few days ago but no response.



#4 Channel Hopper

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Posted 07 December 2017 - 07:46 PM

I can't help further on the sensor values, but regardless of the connector compatibility, I can see there would be potential differences on the display requirements in the US as follows;

when it comes to the radio bands (there is an additional weather/emergency channel frequency allocation Stateside),

DAB and other digital services are satellite based rather than terrestrial over there, and

the dimension of fuel differs if you have an economy setting in the unit, about 16%.

 

What might also need to be considered is the possibility this unit is for the much larger European market where the dashboard is to the right of the driver, meaning the primary HVAC controls could be reversed in the matrix, but not in the new controller. 

 

Did the supplier state a list of vehicle models with years that this would fit, or any exclusions ? When I have bought via Alibaba in the past I found images of equipment where the item culd not possibly have worked, they were very good at using generic photos a lot.