P1188

Code

DS P — Powertrain

Multifunction double relay control malfunction

Brand: DS

Type: P — Powertrain

Views: UK: 1 EN: 9 RU: 5

AI status

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Page language: EN

Causes

Defective multifunction (double) relay or internal contacts
Blown or corroded fuse supplying the relay
Open, shorted or intermittent wiring between relay, fuse and control module
Poor or corroded relay socket/connector pins or grounds
Water ingress or physical damage to relay or harness
Faulty control output (driver) in the engine/BCM/ECU

Symptoms

Intermittent or permanent failure of the system(s) fed by the multifunction relay (no start, no crank, fuel pump not powered, loss of certain accessories)
Multiple unrelated electrical faults or modules failing when ignition is on
Warning lights illuminated on dash (engine light, ABS, etc.)
Vehicle intermittently stalls or will not restart
Unusual clicking or no sound from relay area when key is turned

What to check

Read freeze frame and full module data with a capable scan tool; note when the fault sets and any related codes
Visually inspect the multifunction relay and its socket for corrosion, heat damage or loose pins
Check related fuses and power supply at the relay with ignition ON and OFF
Wiggle-test the relay and harness while watching live data or observing symptoms
Measure supply voltage at relay power pins (should be battery voltage ~11–14V with ignition on)
Back-probe the relay control pin and verify control signal from the module when relay should operate

Signal parameters

Supply voltage to relay power terminal: about battery voltage (normally 11–14 V with ignition ON / engine running)
Control/coil drive signal: low (≈0 V) when de-energized, pulled to battery voltage (≈11–14 V) or driven by module when energized (verify with wiring diagram)
Typical relay coil resistance: commonly ~50–200 ohms for standard 12V relays (verify spec for manufacturer relay)
Switch contact voltage: when closed, should be near battery voltage at the relay output terminal under light load
No-load continuity: relay coil should show continuity (ohms) and contacts open/closed depending on coil energization

Diagnostic algorithm

Retrieve and record all stored codes and freeze-frame data. Note conditions when P1188 set (ignition on, cranking, running, after rain, etc.).
Visually inspect relay, socket, fuse box and wiring for damage, corrosion or moisture. Replace corroded connectors or clean and protect.
Check fuses supplying the relay. Replace any blown fuses and retest. If fuse blows again, suspect short downstream.
With a multimeter, verify battery voltage at the relay supply terminal and good ground at relay ground pin.
Using a scan tool or by commanding the relay, actuate the multifunction relay while back-probing the control and supply pins. Verify the control module is commanding the relay and that the coil and contacts respond.
If relay fails to energize despite proper control signal, remove and bench-test the relay or swap with a known-good relay of identical type. Replace if faulty.
If relay energizes but controlled circuits do not receive power, trace continuity from relay output to the affected module/component; repair open or high-resistance wiring or connectors.
If control signal from the module is absent or abnormal, trace wiring back to the module and check for shorts to power or ground. Consult wiring diagrams for pin identification.
If wiring and relay are good but fault persists, suspect module driver fault. Confirm with a second known-good module or manufacturer-level diagnostics before replacing an ECU/BCM.
After repairs, clear codes and perform test drive or reproduction steps to confirm the fault does not return.

Likely causes

Relay failure or intermittent contact in relay socket
Loose, corroded or damaged connector at relay or fuse box
Blown fuse feeding the relay
Open or short in control or supply wiring between the module and relay
Faulty module driver (ECU/BCM) after wiring has been verified

Fault status

⚠️ Status

P1188 — Multifunction double relay control malfunction. Control module detected an abnormality in the control or power circuit for the multifunction (double) relay. Inspect relay, fuses, wiring and module driver output. Replace components only after confirming wiring and module signals.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-3.0 hours

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