This problem appears to be pretty common on high mileage D's. And it may very well be the CCU board. I received a CCU from an 83 300D the other day that I got from a salvage yard. The board is enclosed in a plastic box that looks like it can be opened up but am still trying to figure out how.

The box has slits that is probably for venting. I sprayed contact cleaner thru the slits and the cleaner residue that came out looked blackish. This tells me it gets dirty in there (after 20+ years).

I'm still trying to figure out how to open the box to get to the board. Someone said that the circuit board may develop cracks and open some circuits which then requires some soldering. Spraying contact clleaner maybe all it needs.

The other thing I am trying to figure out is how to remove the CCU from the car. I'd like to swap the units when I figure out how to remove it.

Any info would be apreciated.

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the sooner you start... the sooner you'll get done If it ain't broke, don't fix it.. Its always simpler to tell the truth...
2007 Honda Accord EX
2007 Honda Accord SE V6
96 C220
97 Explorer - Found Another Home
2000 Honda Accord V6 - Found Another Home
85 300D - Found Another Home
84 300D - Found Another Home
80 300TD - Found Another Home
Previous cars:
96 Caravan
87 Camry
84 Cressida
82 Vanagon
80 Fiesta
78 Nova
Ford Cortina
Opel Kadet
68 Kombi
Contessa

I've replace the control unit twice, is that the ccu you are talking about? I'm very leery of replacing it again, especially with a new one. I may just take it into the shop. I'll explain everything so that way if it goes up again, its on them and I won't have to spend more cash on it.

As for removing the ccu, if its the one that sits behind the bottons on the center console, then its easy to remove.

Have you checked the resistance level of the wiring? Yes, the Aux water pump does draw power from the CCU, that is why many people, myself included, installed a 1 amp fuse in the power circuit of the aux wp.

That chirp sounds like a capacitor when it blows.

Have you tested the blower motor off of the battery? Have you also tested or unplugged the auw wp? Stiff motor bearings or soemthing preventing the motor from spinning will result in higher amp draw, which in turn will cause blown fuses or components.

__________________
RRGrassi


70's Southern Pacific #5608 Fairmont A-4 MOW car

13 VW JSW 2.0 TDI 193K, Tuned with DPF and EGR Delete.

99 W210 E300 Turbo Diesel, chipped, DPF/Converter Delete. Still needs EGR Delete, 232K

90 Dodge D250 5.9 Cummins/5 speed. 400K

Gone and still missed...1982 w123 300D, 1991 w124 300D

No I haven't tested the motor yet, I probably should be considering I suspect the motor. I was more going to test it for bearing play. Now I should test the aux water pump. Is it accessible where I don't have to remove anything to test it?

Some more info, the chirp I heard was clearly under the dash near the blower motor so that's my suspect.

How would I test the resistors? Where are they located? What values should I be looking for?

probably easier to test the auxilliary pump, particularly since it is known to cause this problem. should be easily accessible if it's anything like the 123.

__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

I believe that both the blower motor and the auxiliary water pump motor are powered through the CCU. I would test both of them before installing another CCU.

The blower motor is powered independently of the CCU.

However, the aux. water pump is a common failure and it will take out the CCU if it does not rotate. Don't ask how I know this.

If the aux. pump is not turning, it will burn the circuit board on every CCU that you put in there.

So, you must go and remove the aux. pump and test it with 12V. It's located between the two firewalls. The easiest way to get it out is to remove the section of the forward firewall to give you some room to work. If you remove the firewall section, you can have the pump out in less than 30 minutes.

Test it with 12V and ground. If it does not rotate, you've found your problem. BTW, you'll need another CCU.