2000 Mercury Mountaineer 4WD Lights Flash

2000 MERCURY MOUNTAINEER
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DMKEENER
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  • 1 POST
I own a 2000 Mercury Mountaineer, 4WD, 6 cyl., with 84,000 miles on it.
Within the last week, the dash lights 4WD low and 4WD high flash six times and then go off. Sometimes this process repeats itself once or twice in a half hour period. After that they normally do not flash again until the engine has been shut off and restarted. It does not do this every time. I called the dealer and they said there was a 50%chance that they could diagnose the problem but that if the lights were not on when I took it in, it was less % than that. I could not find anything in the owners manual about the lights flashing and then going off only if the lights stayed on.
Any ideas on what I might do.
Jan 18, 2007 at 10:53 AM
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SQM
  • ✓Experienced Mechanic
  • 6,383 POSTS
Hello,

You likely have an intermittent issue with the transfer case control module.
The best way to know what is the exact issue it will need to have the vehicle scan for codes. But it may not produce any fault codes if the issue is not surfaced at the time of the diagnostics.

This can also be triggered by the relays for the transfer case. Those relays are located under the dash on the passenger side.

https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit

Please let me know of any questions.
Thank you.
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Sep 16, 2021 at 3:27 PM

Suggested Repair

Scan the vehicle for transfer-case codes, noting that an intermittent fault may not set a code if it is not present. Also check the transfer case control module and the transfer-case relays under the dash on the passenger side.

Conversation Summary

The owner of a 2000 Mercury Mountaineer reports that the 4WD Low and 4WD High dash lights intermittently flash six times and then go off, sometimes repeating once or twice before remaining off until the engine is restarted. The dealer said diagnosis would be uncertain if the lights were not flashing. The expert says the likely cause is an intermittent transfer case control module fault and recommends a code scan, while noting that no codes may appear if the fault is not active. The transfer-case relays under the passenger-side dash can also trigger the symptom and should be checked.

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