Rolls Royce HVAC bad

Lahaina-AR
Posts: 2
Joined: 14 Apr 2020, 02:50

Rolls Royce HVAC bad

Postby Lahaina-AR » 14 Apr 2020, 04:05

Hello hoping someone can help read hvac control unit ecu. (LITTLE BACK GROUND) Customer brought car blower motors not working, its been to 2 other shops before coming to me. Customer said first shop said hvac unit was bad sent in for repair and got lost in the mail. Second shop ordered a new hvac control unit and could not get it to work (would not give car back to customer for 2 weeks?) Finally customer brought it to me. Checked all wires and relays all ok, looked at the hvac unit plugs on the unit could be swapped which would send alternator voltage to ground pin. started checking components on the hvac unit found dead darlington array, ordered spare replaced but while replacing overheated and blew the capacitors, installed similar caps. relays started coming on and off stays on for a bit clicks off. found that old PIC16F74 (PLCC 44PIN) has 10ohm between vcc and vss. Orded new PIC16C74A installed rail voltage stays at 4.9 volts. But the board is not powering the relays now.
Ok is it possible to read PIC16f74 using Orange5 and transfer the data to the new PIC?
Thank you sorry for the long write up.

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avital
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Re: Rolls Royce HVAC bad

Postby avital » 14 Apr 2020, 14:48

First of all, you installed a microcontroller without a pre-loaded program, so it can't work well.
The second thing, if the original MCU has a short circuit, you will not read it because it is damaged, you can try to read this PIC16F from another same module, but then you have to be lucky that it is not protected because 50-60% of commercial products are set to read protection.
Польская шляхта www.ecuserwis.pl

Lahaina-AR
Posts: 2
Joined: 14 Apr 2020, 02:50

Re: Rolls Royce HVAC bad

Postby Lahaina-AR » 15 Apr 2020, 15:53

Ok figured as much thank you. New board is 4K hoping I could’ve keep some money for myself hehe.


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