P1774 Low coast brake solenoid valve function fault in a Nissan or Infiniti RE5R05A 5-speed automatic

Nissan/Infiniti P1774 low coast brake solenoid

Severity not verified — if the car runs badly, have it inspected

Owners report clanking, dropping to first gear and a burning smell with this code, but we found no source that says how far it is safe to drive.

It gets more serious if:

  • Inspect soon: The transmission drops into one gear, clanks, slips or smells burnt.

Source: how we rate severity

P1774 in short

On Nissan and Infiniti vehicles with the RE5R05A 5-speed automatic, P1774 means the computer sees a wrong gear ratio when it uses the low coast brake solenoid. Causes include the solenoid, valve body, slipping low coast brake, a switch or sensor, or the computer. Owners report limp mode; get it checked soon.

The low coast brake holds the transmission in a low gear for engine braking. The computer commands its solenoid and then compares engine and shaft speeds; if the gear ratio is not what it expects, it sets P1774.

A parts-maker chart lists the solenoid, the valve body, a slipping low coast brake, pressure switch 2, the park/neutral switch, the output speed sensor and the computer as possible causes, so a sensor or switch problem can look like a transmission failure.

Infiniti lists P1774 in a 2010 diagnosis bulletin for the same transmission. Owner complaints on 2007-2008 Pathfinders and a 2007 Frontier describe limp mode, clanking and a burning smell, and one owner blames coolant mixing from the radiator cooler.

Pick your make

P1774 is a manufacturer-specific code: its meaning depends on who built the car.

Other makes: meaning not verified. Check with a scan tool that reads manufacturer definitions.

Most likely causes

  1. Low coast brake solenoid fault

    Supported by vehicle data
    Why it ranks here
    The code is named for this solenoid and the parts-maker chart lists it first.
    What would change this
    Rises if solenoid resistance or response is wrong. Falls if it tests normal.

  2. Faulty pressure switch 2, park/neutral switch or output speed sensor

    Supported by vehicle data
    Why it ranks here
    The computer judges the gear ratio from these inputs, and the chart lists each as a cause.
    What would change this
    Rises if live data from these inputs is erratic. Falls if the readings are steady and sensible.

  3. Worn valve body or slipping low coast brake

    Supported by vehicle data
    Why it ranks here
    Owner reports of clanking and dropping to first gear fit internal wear, and the chart lists both.
    What would change this
    Rises if electrical tests pass and the transmission slips or smells burnt. Falls if an input fault is found.

  4. Coolant in the transmission fluid from the radiator cooler

    Possible — needs testing
    Why it ranks here
    One Frontier owner links the code to cooler failure, but this is an owner opinion and not a bulletin.
    What would change this
    Rises if the fluid is milky or the radiator cooler fails a pressure test. Falls if the fluid is clean.

  5. Transmission computer fault

    Supported by vehicle data
    Why it ranks here
    The chart lists the computer last, after the solenoid and inputs.
    What would change this
    Rises only after wiring, inputs and solenoid test good. Falls if any of those is faulty.
    How to test the transmission control module (tcm)

What to test first

Start at step 1. Each result tells you what it means and where to go next.

  1. Read all codes and freeze-frame data, and check the fluid level, colour and smell.

    Low riskTool: OBD-II scan tool

  2. Have a shop check the low coast solenoid resistance and the pressure switch 2, park/neutral switch and output speed sensor readings.

    Best left to a shopTool: scan tool with live data, multimeter

    Warning:Further testing means removing the transmission pan or valve body; leave it to a shop.

Symptoms

  • Check engine light on
  • Transmission drops to first gear or has fewer gears Gets more serious: stop and have it checked.
  • Clanking noise or burning smell Gets more serious: stop and have it checked.

Compare with: Check engine light with loss of power

How to fix

  1. Check the transmission fluid level and condition, following the owner's manual.

Parts and cost context

  • Transmission control module (TCM):Replace the computer last; the chart lists several cheaper causes first.

Labor varies by vehicle and shop; get a quote before you approve a repair.

Compare used part prices on PartPriceGuide

On your vehicle

Nissan

  • 2007–2008 · Pathfinder

    Supported by vehicle data

    Owners of 2007 and 2008 Pathfinders report P1774 with limp mode, clanking and a burning smell.

  • 2007 · Frontier

    Possible — needs testing

    A 2007 Frontier owner read P1774 with P0717 and links it to coolant mixing from the radiator cooler (owner opinion).

Infiniti

  • ITB-10-006AStatus unverified

    INFINITI: 5 SPEED A/T DTC DIAGNOSES FOR P1701, P1702, P1703, P1704, P1705, P1754, P1759, P1764, P1769, P1774.

    2003–2010ex35, fx, fx35, fx45, g35, g37, i30, i35, infiniti, j30, m, m35, m45, q45, qx4, qx56 · issued · NHTSA 10033227

    Lists P1774 with other RE5R05A 5-speed automatic codes and points to a repair flow chart, or reports the MIL on with P1774. Only the NHTSA flat-file summary was read, not the bulletin itself.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

  • 04047Status unverified

    MALFUNCTION INDICATOR LAMP (MIL) ON WITH DIAGNOSTIC TROUBLE CODE (DTC) P1774.

    2004qx56 · issued · NHTSA 10010174

    Lists P1774 with other RE5R05A 5-speed automatic codes and points to a repair flow chart, or reports the MIL on with P1774. Only the NHTSA flat-file summary was read, not the bulletin itself.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

  • P1757Front brake solenoid circuit fault in a Nissan RE5R05A-type 5-speed automatic

    Same system Supported by vehicle data

    P1757 is the front brake solenoid code on the same RE5R05A transmission and the same chart.

All Transmission codes

Sources and review

  1. RE5R05A Trouble Code Chart — Sonnax Transmission Company ,
  2. NHTSA complaint 1504451: 2007 Nissan Pathfinder, P1774 — NHTSA (owner complaint)
  3. NHTSA complaint 1383999: 2008 Nissan Pathfinder, P1774 low coast brake — NHTSA (owner complaint)
  4. NHTSA complaint 1379623: 2007 Nissan Frontier, P1774 and P0717 — NHTSA (owner complaint)
  5. Infiniti bulletin 04047: MIL on with P1774 — Infiniti (Nissan North America) ,
  6. Infiniti ITB-10-006A: 5-speed automatic DTC diagnoses (RE5R05A) — Infiniti (Nissan North America) ,
  7. Cal. Code Regs. Tit. 13, § 1968.2 — Malfunction and Diagnostic System Requirements (OBD II) — California Air Resources Board (via Cornell LII)
Last reviewed
Written by
Saurabh K.
Editorial review
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Technician review
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