The engine cranks but will not fire due to a lack of communication from the ECU.
The B58944 is engineered for extreme automotive environments, serving as a core component in both petrol and heavy-duty diesel board architectures. Repair technicians frequently encounter this chip when servicing the following systems available at specialty stores like ECUFixTool :
: Check for discoloration, microscopic pin cracks, or blistering on the SOP-28 plastic casing.
+---\/---+ VCC 1| |28 GND I/O0 2| |27 A14 I/O1 3| |26 A13 I/O2 4| NEC |25 A12 A0 5| B58944 |24 A11 A1 6| |23 A10 A2 7| |22 A9 A3 8| |21 A8 A4 9| |20 A7 A5 10| |19 A6 I/O3 11| |18 I/O7 I/O4 12| |17 I/O6 I/O5 13| |16 I/O5 /WE 14| |15 /OE +--------+
If you are sourcing a replacement chip for circuit board repair, you can look for equivalent 32K x 8 asynchronous CMOS SRAMs with a 70ns access speed in a 28-pin SOP package. Direct architectural equivalents include: nec b58944 datasheet
Actively used across Honda passenger cars, Iveco heavy machinery, and Chevrolet/GM platform variants. Understanding Failures and ECU Repair Workflows
The B58944 is typically produced as a leaded, lacquer-coated disk or an encapsulated epoxy bead/probe, offering excellent long-term stability and high accuracy within its operating range. 2. NEC B58944 Key Specifications (Datasheet Summary)
The B58944 is housed in a , a surface-mount design featuring 28 pins intended for efficient PCB integration. Technically, it is closely related to the D43256BGU series, which is a 256K-bit (32K x 8) CMOS static RAM. Its primary role in an ECU environment is to handle data storage or engine-driving functions that are essential for real-time vehicle management. Package Type: SOP-28 Manufacturer: NEC (often branded or used in Bosch modules)
| Category | Example NEC Parts | B58944 Similarity | |------------------------|-----------------------------|-------------------| | Bipolar transistor | 2SB589 (PNP, if existed) | Possible, but no record of 2SB589 | | Diode array | D58944 | Not standard | | Custom ASIC / Hybrid | B5xxxx series (some hybrids) | Most likely | | Date/lot code | B58944 on package surface | Not a datasheet part number | The engine cranks but will not fire due
In this context, it is almost exclusively associated with , a leading global automotive supplier. Furthermore, based on the parts often listed alongside it, the NEC B58944 is most likely a memory component, specifically a static RAM (SRAM) chip , used by the ECU's main processor as temporary data storage. The designation "B58944" is a proprietary Bosch number, and the term "NEC" refers to the original manufacturer of the underlying silicon chip (NEC Electronics, now part of the Renesas Electronics corporation).
Reading or writing the B58944 chip often requires . Using OBD tools requires backing up injector codes separately, as they can be lost during the read/write process. Specific tools recommended for this include Kess, K-TAG, CMD, and BDM100 for BDM access, while MPPS v13/v16 can be used for OBD access but increases the risk of losing injector codes.
The B58944 is a "vulnerable" component, meaning it is frequently the culprit when an ECU fails. It is found in several Bosch ECU families:
The is a robust and highly accurate sensor designed for reliable performance in temperature-critical applications. By understanding its R/T curve, minimizing self-heating, and utilizing high-precision circuits, engineers can implement effective temperature sensing solutions. +---\/---+ VCC 1| |28 GND I/O0 2| |27
Technicians must utilize a temperature-controlled hot-air rework station to lift the bad SOP-28 package without ripping the delicate copper circuit pads off the multi-layered ECU board. Procuring Replacement Parts
Before moving on, it's crucial to clarify a common point of confusion. The identical string "B58944" is also used to classify an manufactured by Borosil Scientific, designed for lab analysis of fine crystalline precipitates. While this is an interesting coincidence, it is completely unrelated to the IC we are discussing.
Delivers a stable +5V regulated power rail from the ECU's main power management IC.