A dead battery, a jump start, or welding on the frame is the classic way a Cat 70-pin ECM gets hurt. Here is the 60-second check that tells you whether it is the ECM, and what to rule out first.
Sale through October 31: $525 on every Cat 70-pin repair (regularly $745). Paid at checkout, full refund if we can't fix it. Failed flash recovery available.
Do this: turn the key on and watch the dash. The check engine light should come on for a few seconds and then go out.
If the light never comes on: the ECM is probably not waking up. That is the single most common sign of a failed 70-pin ECM after a battery event.
If the light comes on and it still will not start: the ECM is alive, so look at fuel, the key-on and start circuits, and the engine side before blaming the module.
Battery voltage at the ECM power pins with the key on. A weak or sulfated battery can look exactly like a dead ECM.
Grounds. A corroded or loose ground at the block or frame is behind a surprising number of "dead ECMs".
ECM fuses and the main relay. A jump start in the wrong order can blow these without hurting the module.
Power and ground are clean at the ECM connector, the fuses are good, and the check engine light still will not come on. At that point the module is the problem.
Other common signs: cranks but no injection, no communication with the diagnostic tool, or the ECM forgets its engine serial number after power is restored.
Rule of thumb: power, grounds, and harness first, module second. We bench-test every unit, so if the ECM isn't your problem, we'll tell you that too.
Component-level repair, bench test, and your original programming stays with your module. About 3 to 5 days on the bench. You pay the repair price at checkout, before you ship it. Any normal failure we can't fix, you get a full refund. The exceptions are when the ECM itself is the reason: a board that is cracked, burned, or eaten by water and corrosion, a proprietary chip that is no longer made, or damage from an earlier repair attempt. In those cases, and if your ECM tests good with nothing wrong, $150 covers the bench test, the written report and the return shipping, and we refund the rest.
Most likely the ECM is not waking up, but check battery voltage, grounds and the ECM fuses first. If power and ground are clean at the ECM connector and the light still stays off, the module needs repair.
Yes. Reversed polarity, a voltage spike, or welding on the frame without disconnecting the batteries can damage a 70-pin ECM. The module is repairable in most cases.
$525 flat through October 31 (regularly $745), about 3 to 5 days on the bench. You pay at checkout before you ship it, and any normal failure we cannot fix is a full refund.
More Cat ECM symptoms: Cat 70-pin ECM problems & symptoms · Corroded Pins on a Cat ECM Connector · Cat ET Won't Connect to the ECM · Cat Dead Cylinder With Good Injectors · Cat Throws Many Sensor Codes at Once
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