In short
- OEMs send rolling schedules and EDI releases, not one-off purchase orders.
- JIT delivers on time; JIS delivers in the exact model-mix sequence of the line.
- The ASN (advance shipping notice) tells the OEM what is arriving, before it arrives.
- ERP that ingests releases and raises ASN automatically is what protects the delivery rating.
How OEMs actually order: schedules, not POs
A car or CV OEM does not send you a purchase order for 5,000 parts. It sends a delivery schedule, a rolling document with firm quantities for the near term and forecast quantities further out, updated frequently. Large OEMs transmit these as EDI releases (in formats such as 830 for planning and 862 for shipping). Your job is to convert firm demand into production and material plans while using the forecast to plan capacity and long-lead buys. Doing that by re-keying a PDF into an order screen is where most delivery problems begin, which is why Tier-1 supply depends on schedule intake.
JIT and JIS: on time versus in sequence
Two terms cause confusion:
- JIT (Just-in-Time) means the part arrives exactly when the line needs it, no early stockpiles, no late stoppages.
- JIS (Just-in-Sequence) is stricter: parts arrive in the exact order the OEM will consume them, matched to the model and colour mix rolling down the line.
JIS is common for large, variant-heavy parts (seats, bumpers, harnesses). Getting it wrong stops the OEM line, so sequenced build and dispatch have to be driven from the OEM broadcast, not from a spreadsheet. This is where production planning earns its keep.
See how this runs on your own part numbers, schedule to dispatch.
The ASN: telling the OEM what is coming
The Advance Shipping Notice (ASN) is the electronic message that tells the OEM exactly what is on the truck, part numbers, quantities, lot and pack details, before it arrives, so their receiving and line-feed can prepare. A clean ASN, with correct barcode or QR labels, means smooth receipt and no manual counting at the gate. A wrong ASN means rejections and delivery-rating hits. The ASN should be generated in the same system that holds the schedule and the dispatch, alongside the GST e-invoice and e-way bill, so everything reconciles automatically.
Where suppliers lose the delivery rating
OEMs score suppliers continuously on delivery and quality. The common failure points:
- Schedules re-keyed manually, so a change is missed.
- No link between the forecast and long-lead procurement, so material runs short.
- Sequence errors in JIS dispatch.
- ASN mismatches at the OEM gate.
- No live view of promised versus actual dispatch until it is too late.
Every one of these is a systems problem with a systems fix.
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How ERP turns releases into on-time dispatch
The pattern that protects your rating:
- Ingest EDI/schedule releases and convert them to firm and forecast demand automatically.
- Drive JIT/JIS pulls and a buildable, finite-capacity plan.
- Plan long-lead buys from the forecast, not from panic.
- Raise the ASN, labels, e-invoice and e-way bill together at dispatch.
- Track promised versus actual on a live delivery dashboard.
When releases flow straight into the plant and out as clean ASN, on-time delivery stops being a daily fire drill.
Key Takeaways
- OEMs order via rolling schedules and EDI releases, not one-off POs.
- JIT = on time; JIS = in the exact line-consumption sequence.
- The ASN pre-tells the OEM what is arriving; errors cost the delivery rating.
- Link forecast to long-lead procurement to avoid material shortages.
- ERP that ingests releases and raises ASN automatically protects on-time delivery.
Frequently Asked Questions
A rolling document from the OEM with firm near-term quantities and forecast quantities further out, updated frequently and often sent as an EDI release (e.g. 830/862).
JIT (Just-in-Time) delivers parts exactly when needed; JIS (Just-in-Sequence) delivers them in the precise order the OEM line will consume them, matched to the model mix.
An Advance Shipping Notice, an electronic message telling the OEM exactly what is on the incoming truck, part numbers, quantities, lot and pack details, so receiving and line-feed can prepare.
Yes. An automotive ERP ingests EDI/schedule releases, converts them to firm and forecast demand, drives JIT/JIS pulls and raises the ASN at dispatch.
By removing manual re-keying, linking forecast to procurement, sequencing dispatch correctly and generating clean ASN, then tracking promised versus actual on a live dashboard.
Conclusion
OEM schedules, EDI, JIT/JIS and ASN are the operating rhythm of automotive supply, and the delivery rating that decides your business is won or lost in how well you run them. For Chennai suppliers, the fix is systemic: ingest releases directly, plan to real capacity and lead time, sequence the build, and raise clean ASN at dispatch, all in one platform. Do that and on-time delivery becomes routine instead of a scramble.
Turn OEM releases into on-time dispatch
Talk to our Chennai team, or book a free demo and see it on your own part BOM.