Motorola MC68HC908 2J74Y

[jojoe]

mc68hc908

Hi everybody,

I have a problem with this processor & wondered if any of you knowledgeable people would care to help me with it.

The processor controls the instrument panel in my car & it misbehaves when the ambient temperature is low. If the temperature is 20°C there is no problem...lower than this & the instruments in my car will not work correctly until the processor warms up.

From my research I have found out that the problem comes from poor programming at the production stage.
From what I have read if the processor is dumped at room temperature (when it is working fine) then re programmed with the same dump it cures the problem.

I have a very limited electronics knowledge & I do not have the equipment to re programme the processor.

Would any of you be able to help out?

Many thanks.

Regards, jj

 

[wp100]

mc68hc908 programmer

Hi,

The 'TT' forum makes interesting reading on that dash panel - unfortunately as they say even if it is the chips programming core that is faulty, getting it replaced or reprogrammed is very difficult if the manufacturer won't co-operate by supplying new chips.

Like 99% of all circuit board failures its usually down to just one simple item - but its the time and trouble to locate and replace it thats always the problem - which certain companies milk with glee.

I would think there might be someone around with a detailed knowledge of how to extract the data and reprogram it into new chips etc, but think you would be perhaps better doing that on a group basis and so being able to offer the guy some financial incentive as that chip is used more in the commercial world rather that the hobbyist.
As mentioned in that post - there is still a chance that it may be a multiple fault or something else such as the crystal or other components or even a faulty circuit board.

 

[jojoe]

motorola mc68hc908

Hi wp100,
Yes I have seen the TT forum...I am Tel boy on that forum.

I know it is the chip at fault as with the help of a guy on the TT forum I built a "Chip Heater" to warm the chip to stop the fault condition.

Details here:
**broken link removed**

The fault does seem to be slowly getting worse though...at first the fault only seemed to occur if the temperature was below 10°C.....but now the temperature has to be approx 20°C before the instruments work. I know this as I disconnected the heater for the summer months only to find the fault happening again.

I suppose I'm trying to find someone that could read & reprogramme the chip for me as a project....I thought about buying a programmer & giving it a go myself but that could take a long time learning to operate the programmer etc...

I have helped lots of people over the years & I just wondered if I could find a like minded person who likes a project & to help others out.

Cheers. jj

 

[wp100]

2j74y

Hi,

Looking at those links it looks like its wide problem across various makes.

As to the exact problem - well only fitting a new chip reprogrammed will really prove the fault is the chip or something like a 'dry' joint on the chip pins or a cracked track under it . A board like that is exposed to a lot of vibration and a 'cold' joint can give identical symptoms as I have expereinced many times on machines at work.
It may well have been manufactured using the new Lead Free solders with are known to have a lot of problems - thats why medical and defense equipment still use lead base solders - so I'm told.

I assume you only have the one board, in your car, if you do have an old one, you could get someone skilled at SMD soldering to remake those joints to see if that cures the problem before replacing it - but be aware that doing so also has a chance of destoying the chip if you are unlucky.

My own thoughts on an original programming temperature problem cured by reprogramming doesn't sound quite right -but will happily hold my hands up if it was .

These forums are aimed more at the hobbyist and the Motorola chips are not mentioned much at all - let alone having one of their programmer devices.

You might be better contacting the Freescale forums ( the new name for motorola micros ) .

Think the price for that board is not too bad though - I need a new oxygen sensor for my old Avensis - most cars - its a £25 -50 part - Toyota want £325 !!

Added after 30 minutes:

Hi again,

Forgot to mention that sometimes we have unusual boards go faulty at work that are not ones we would attempt to repair or have the info on, but there are specialist circuit board repair conpanies who have some very clever machines that can analyse and diagnoise problems very quickly resulting in a low cost repair.

I know my colleague uses on such place in Liverpool but I'm sure there are many others more local to you - I 'm told its better if you can walk in with the board and explain the problem in person - so you get a quicker and cheaper repair.

 

[jojoe]

2j74y motorola

I assume you only have the one board, in your car, if you do have an old one, you could get someone skilled at SMD soldering to remake those joints to see if that cures the problem before replacing it - but be aware that doing so also has a chance of destoying the chip if you are unlucky.

Yeah just the one board.
I have remade the joints on the legs of the processor so it's not a dry or cracked joint on them, of that I'm certain.

My own thoughts on an original programming temperature problem cured by reprogramming doesn't sound quite right -but will happily hold my hands up if it was

I know...thats why I would love to read & reprogramme the chip to confirm this.

The advice John on the TT forum gave me regarding the processor memory getting worse over time and the working temperature range of the chip eventually diminishing seems to be spot on .....It does seem a very strange coincidence that when the temperature is low & the fault happens a quick 5 second blast of my "Chip Heater" cures the problem.

Think the price for that board is not too bad though

What board...what price?

There are a few companies that specialise in repairing car dash boards....this costs about £150-£200 with a 2 year warranty, not bad I suppose compared to your oxygen sensor ....but I love to meddle on with stuff & love to get a result hence my posts on here & the TT forum...it's honestly not just about saving money.

The Freescale forums may be a good place to try :wink:

Cheers, jj

 

[jojoe]

68hc908 project

Hi,
Do you think I would have any success with this programmer?

http://www.car2diag.com/products/603102.html

Cheers, jj