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07 Mack MR688P trying to diagnose air operated radiator fan…

07 Mack MR688P trying to...
07 Mack MR688P trying to diagnose air operated radiator fan clutch. Fan runs 100 % all the time, can ground solenoid and will shut off.
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Answered in 2 minutes by:
3/30/2016
Technician: Daniel Wilson,
 replied 6 years ago
Daniel Wilson
Category: Medium and Heavy Trucks
Satisfied Customers: 14,637
Experience: Owner at DJ Wilson
Verified

Hi Rick, My name is***** you have any fault codes? Is the AC system working properly and fully charged? AC clutch engaged and on when the fan stays engaged? check your AC pressure switches and system charge as well as your fan override switch

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Customer reply replied 6 years ago
I don't have a scanner for this type of truck. Is there a way to get flash codes? AC works poorly haven't checked pressures yet.
Technician: Daniel Wilson,
 replied 6 years ago

The fan will stay engaged when the AC clutch is engaged... E7 engine?

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Customer reply replied 6 years ago
on both.
Technician: Daniel Wilson,
 replied 6 years ago

Mack Except Mid-liner: Accessing Diagnostic Trouble Codes

V-MAC & V-MAC II

Using Electronic Malfunction Lamp

The V-MAC module can blink a two-digit blink code for each of the detectable active faults in the system. These codes are displayed by the instrument panel MIL. They allow for quick diagnosis without using a scan tool.

If there is more than one active fault there is often one root cause. As a general rule, begin with active faults that involve sensors.

To diagnose malfunctions with blink codes, proceed as follows:

  1. Turn ignition On, then wait until MIL’s two second power-up test has finished.

  2. There must be an active fault which keeps lamp on after power-up test.

  3. Turn speed control switch Off, then press and hold SET/DECEL or RESUME/ACCEL switch until MIL goes out.

  4. After approximately one second, the V-MAC module will begin blinking out its two-digit blink codes. The two digits of each code will be separated by a one second idle time (MIL out).

  5. Each blink code digit may consist of up to eight on–off flashes. The on and off time for each flash will be 1/4 of a second.

  6. Count the MIL on flashes to determine two digit blink code.

  7. Only one active fault will be blinked per request. There must be a separate request for each active fault if there are multiple active faults present. To display additional faults, hold in SET/DECEL or RESUME/ACCEL switch until MIL goes out. Blinking sequence will begin again after a one second delay.

  8. If fault blinking request is repeated while V-MAC is in process of blinking an active fault, that sequence will stop and next active fault will display.

  9. If an active fault is cleared while V-MAC is blinking that fault, procedure will not stop.

  10. MIL will return to normal functions after every complete blinking sequence and will remain on for active faults and off for inactive faults.

  11. If more than one fault is present, continue blink code sequence until first active fault is displayed again to ensure all faults have been accessed.

See what you get for flash codes

V-MAC III

Blink Codes

The V-MAC III system is capable of flashing a two-digit blink code for each detectable active fault in the V-MAC III system. These codes are displayed on the Electronic Malfunction Lamp (EML) which is located on the dashboard.

The primary reason for the blink code is to allow quick diagnosis of active faults in the system. To properly diagnose the system, a diagnostic computer is required. To access the blink codes, proceed as follows:

  1. Turn ignition switch to ON position.

  2. Wait until EML's two-second power-up test is finished. There must be an active fault for lamp to remain ON after two-second power-up test.

  3. With speed control ON/OFF switch in OFF position, press and hold SET/DECEL switch until fault lamp goes OFF.

  4. Fault lamp will remain OFF for approximately one second.

  5. Immediately after wait time, VECU will begin to flash a two-digit blink code.

  6. Two digits of code will be separated by a one second idle time (fault lamp OFF).

  7. Each digit of blink code may consist of up to nine ON/OFF flashes.

  8. ON and OFF time between each flash will be one quarter second.

  9. ON flashes of fault lamp must be counted in order to determine two-digit blink code.

  10. Only one active code will be blinked per request.

  11. There must be separate request for each active fault, where there are multiple active faults present in system.

  12. To request another code be displayed, hold in SET/DECEL switch until fault lamp goes OFF.

  13. Blinking sequence will begin again after a one second delay.

  14. If code blinking request is made while VECU is in process of blinking an active fault, that sequence will stop and next active code will be blinked.

  15. If an active code is cleared while VECU is blinking that fault, procedure will not stop.

  16. After every complete blinking sequence, fault lamp will return to normal. It will remain ON for active faults and OFF for inactive faults.

  17. VECU will provide blink codes for active faults registered by both VECU and Engine Electronic Control Unit (EECU).

  18. Software will not provide codes for inactive faults. Accessing inactive fault tables of VECU and EECU requires using a Pro-Link 9000 or diagnostic computer

V-MAC IV

Basic Display

On models equipped with the basic display, three different screens of information are available to the operator. The current conditions screen displays the current mileage, time, temperature and system voltage. The Trip Information screen displays mileage, time, temperature and system voltage for the trip the vehicle is presently on. The diagnostic screen allows the operator to access inactive and active fault codes stored in the V-MAC system. There is a button located under the basic display that the operator uses to change the display.

Co-Pilot Display

On models equipped with Co-Pilot Display (in-dash computer), the operator can display vehicle information supplied by the V-MAC system. The Co-Pilot display shows the current status of vehicle information. The information area in the center of the display is used to show system diagnosis and operating conditions. The stalk switch mounted on the steering column is used to navigate through the information the display computer provides.

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Customer reply replied 6 years ago
How can I reach you after we have down the test?
Technician: Daniel Wilson,
 replied 6 years ago

We can post back and forth as needed. You can access this chat by the e mail you used to post your question

Daniel Wilson
Category: Medium and Heavy Trucks
Satisfied Customers: 14,637
Experience: Owner at DJ Wilson
Verified
Daniel Wilson and 87 other Medium and Heavy Trucks Specialists are ready to help you
Ask your own question now
Customer reply replied 6 years ago
Sorry done the tests!Thanks
Technician: Daniel Wilson,
 replied 6 years ago
Phone call session started
Technician: Daniel Wilson,
 replied 6 years ago

What did you get for codes?

It only pulls active codes if any.

If the AC is not functioning properly that will cause the fan to stay on or if there is a harness problem or faulty AC pressure or engine temp sensor or harness. Check the harness first and also check the fan relay and AC relays and fuses. Swap with a known good one.

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Customer reply replied 6 years ago
Hi I was getting back to this truck. Do you have a diagnostic chart or an electrical blowup for the fan clutch circuit?
Technician: Daniel Wilson,
 replied 6 years ago

The link I posted did not com through? Let me know and if not I will see what I can do when I get back from my appointment. On my way out now actually.

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Customer reply replied 6 years ago
Do you have time to send over a wiring diagram for the fan clutch?
Technician: Daniel Wilson,
 replied 6 years ago

I did some digging and found the service bulletin with the schematics. Click below

Service bulletin

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Customer reply replied 6 years ago
Back to the fan clutch issue. This fan clutch is not the same as in the picture that you sent. I believe it's called a Horton clutch, only operated by air pressure only! Do you have a wiring diagram for this fan setup?
Technician: Daniel Wilson,
 replied 6 years ago

Do you have any information or numbers you can get from the hub or upload a picture?

Mack Horton retrofit

Does it look like the link I posted?

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Technician: Daniel Wilson,
 replied 6 years ago

There are so many different fan hubs available and the diagrams will depend on the hub you have. I see the numbers I need in the picture you sent. What are those numbers on the silver sticker?

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Customer reply replied 6 years ago
The label on the fan clutch is Drivemaster Drive Fan Horton
Part # *****
40MH44M
Technician: Daniel Wilson,
 replied 6 years ago

Click on this link.

Troubleshooting and diagrams

Here is the one of the other styles used but it is not the DM. The electrical sections will show you the wiring for the fan hubs both through the ECM and non ECM

Fan hub

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Customer reply replied 6 years ago
Do you have access to the fan clutch to ECM wiring diagram?
Technician: Daniel Wilson,
 replied 6 years ago

Hi, The diagrams I have already posted are what I have.

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Daniel Wilson
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Category: Medium and Heavy Trucks
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