Vehicle Platform & ECU Name DTC Troubleshooting Data Ver: 1 Date: 23/11/2022 Author: ERC Page 588 of 834 Copyright by TATA MOTORS Ltd. This document must not be used in any w ay, such as copying and redistributing to third parties, w ithout our consent P0691-00 : Low Speed Fan Control - Short Circuit to Ground Overview: DTC Code P0691-00 DTC Description as per ISO standard Fan 1 (low speed) Control Circuit Low. ECU Pin Number B68 Customer Symptom Reduced torque Mode is activated. AC will not function. Cooling fans will run in low speed continuously. Engine over temperature warning lamp will turn on at lesser engine coolant temperature (8 degrees less than normal condition). Fault Effects (On Vehicle) Reduced torque Mode will be activated. Reduced Vehicle performance. Drive modes will be disabled. Radiator fan will remain run continuously. SPCS injector learning will be disabled. Threshold for Engine over temperature warning lamp turn ON will be reduced. Lamp Status (If Any) CE lamp is on. Fault Detection Condition This DTC gets logged if the Low speed fan control pin of EMS ECU gets short circuit to ground Normal Operating Condition When vehicle is soaked for 8 hours and Engine is cranked keeping AC off then Cooling fans will be in Off condition. Probable Trouble Area Fan circuit wiring harness, Low Speed fan relay, HVAC, ECU, Wiring harness Component Details: Cooling Fan circuit consists of two fans. With the help of Relays, cooling fans will be made to run either in Series (Low Speed) or Parallel (High Speed). EMS will decide whether to turn the cooling fans in low speed or high speed based on Engine coolant temperature & AC refrigerant pressure. Preliminary Checks: Check whether the customer voice / view about the issue is matching with the fault effects mentioned above. If yes, go ahead with next steps. If not, check for other DTC’s presence. Check whether similar complaints are earlier reported. If yes, perform the preliminary checks with respect to earlier issue closure. Loose/ Damaged Connections between low speed fan Relay and EMS ECU. Loose/ Damaged Connections between low speed fan Relay and Battery supply or Ground. Check for back out of pins & damage of pins at ECU connector.
RkJQdWJsaXNoZXIy MTIwNTUz