P0889: Transmission Control Module Power Relay Sense Circuit Range/Performance
What to do
If the battery also goes flat when the car is left for a few days, mention it — a relay whose contacts have welded shut causes both, and it is an inexpensive part.
What this code means
The relay sense circuit is reporting a state that does not match what the module commanded — relay confirmed closed when it was told to open, or the reverse. Relay contacts that have welded shut from repeated arcing produce exactly this, and so do contacts too burnt to make properly.
A welded relay is worth recognising because of its second consequence: it keeps the module powered permanently, which flattens the battery over a few days of standing.
Likely causes
Start here
Less common
- Corroded or loose connector · easy
- Damaged module supply wiring · moderate
Symptoms
Components involved
Information, not instruction
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Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
Community experience
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What makes one worth reading:
- The car — make, model, year and engine. The same fault behaves differently on each.
- What you measured, not only what you replaced.
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