PPAP is the evidence that a part was made by the production process, not the prototype process. On a harness, five of its eighteen elements decide whether that was ever true.
PPAP — Production Part Approval Process — is the automotive industry's evidence pack for one specific claim: that this part, made by the production tooling, on the production line, by production operators, at the production rate, meets the specification. It is defined and published by AIAG, the Automotive Industry Action Group, and it applies to production parts and service parts. It is not a certification, it is not a test report, and it is not a promise about the future.
That last distinction is why it is worth asking about during a supplier audit. A sample built by the engineering team in a workshop proves a part can exist. PPAP is how a supplier proves the part that will actually arrive can exist.
The submission has eighteen standard elements. All of them are relevant; not all of them are equally capable of being faked. On a wire harness these five are where the real information sits:
| Element | What it proves on a harness | How to tell it is real |
|---|---|---|
| Process flow diagram | That the sequence from incoming wire to packed carton is actually written down, including which steps are in house. | It names the machines. A flow diagram with no machine numbers was drawn for the file. |
| PFMEA | That the failure modes specific to crimping, sealing and routing have been reasoned about, with actions and dates. | Look for crimp height drift, wrong terminal in the applicator, and wire in the wrong cavity — the three that actually happen. |
| Control plan | That each characteristic has a method, a sample size, a frequency and a reaction plan. | "Visual" against a pull-off force requirement is the tell. |
| Measurement system analysis | That the gauge measuring the critical characteristic is capable — a pull tester with poor repeatability cannot police a crimp. | Ask for the MSA on the pull-force test specifically, not on the callipers. |
| Initial process studies | That crimp height and pull-off force were measured enough times to state a capability index, not just a pass. | A Cpk quoted for a "critical" characteristic with no data behind it is a number, not a study. |
The remaining elements matter, but most of them are documents rather than evidence of process. Dimensional results, material and performance test records, the sample parts and the part submission warrant are the pack's spine; the five above are where a supplier's actual discipline shows through.
Two elements are frequently outside a harness manufacturer's control. Design records come from the customer, and the DFMEA follows the design — which is exactly why our IATF 16949 scope excludes product design under Clause 8.3. A supplier who claims to hold design responsibility they do not have will produce a DFMEA about somebody else's decisions.
| Level | What is submitted | When it is used |
|---|---|---|
| 1 | Part submission warrant only | Mature part, unchanged process, low customer risk |
| 2 | Warrant, samples, limited supporting data | Minor change to an approved part |
| 3 | Warrant, samples, complete supporting data | The default for a new part — the level most OEMs specify |
| 4 | Warrant, plus whatever the customer defines | Customer-specific requirement |
| 5 | Warrant, samples, complete data, reviewed on site | High-risk part, or a supplier being watched |
Level 3 is the working default. When a buyer asks "do you support PPAP", the useful follow-up is "which level, and can I see a submission you have made at that level" — because Level 1 and Level 3 are both technically "PPAP support" and only one of them hands you the control plan and the capability studies.
Four questions get most of the value out of a PPAP conversation:
On our own programmes the answer to the first question is that process flow, PFMEA, control plan, MSA and the process studies are ours, while design records and the DFMEA come from the customer because the design does — see what our IATF scope excludes and why that is the honest answer for a build-to-print supplier.
No, a first article is a subset. A first article report typically covers dimensional results, some material or performance data, and possibly crimp measurements — three of the eighteen PPAP elements. PPAP adds the process reasoning around them: the flow diagram, the PFMEA, the control plan, the measurement system analysis, the initial process studies and the part submission warrant. A supplier who can produce a first article but not a PPAP has measured a part; a supplier who can produce a PPAP has documented a process.
Level 3, which is the warrant plus samples plus complete supporting data, and it is the level most vehicle manufacturers specify by default for a new part. Level 1 hands you a signed warrant and nothing else, which tells you the supplier believes the part is approved without showing you why. Levels 4 and 5 are for cases where you define your own requirement or where the risk justifies reviewing the pack at the supplier's site; a harness going into a first-generation battery programme is a reasonable candidate for Level 5.
The approval is tied to a part, a process and a site rather than to a date, so it lapses on change rather than on a calendar. A new tooling set, a moved or duplicated line, a different terminal or wire sub-supplier, a change in the manufacturing process or a gap in production long enough for the line to be rebuilt all invalidate it and require notification or resubmission. Ask a supplier what triggers a resubmission in their own procedure — a supplier with a working PPAP process can list those triggers from memory, because they have had to use them.
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Learn moreA drawing, a sample, a connector list or a photo is enough to start. Typical reply within one working day, with engineering questions rather than a sales pitch.
