What do you if the security system on your 1991 Jeep Laredo allow to start engine and a light comes that says Check anti-lock?

The "Check Anti-lock" light on a 1991 Jeep Laredo (which likely doesn't have a sophisticated modern security system like a chip key) illuminating while the engine starts suggests a problem with the anti-lock braking system (ABS), *not* the security system itself. The security system, if it even had one beyond a basic ignition switch, would likely prevent the engine from starting at all.

Here's what you should do:

1. Drive cautiously: The ABS is malfunctioning. While you can still drive the vehicle, braking distances will be longer because you're relying on standard braking instead of the ABS's assistance. Avoid hard braking.

2. Get the ABS system checked: The "Check Anti-lock" light indicates a fault within the ABS system. This could be anything from a faulty sensor (wheel speed sensor is common) to a problem with the ABS module itself. You'll need a mechanic to diagnose the issue. A simple code reader might be able to help determine the problem area, but a proper shop visit might be necessary to replace parts.

3. Don't ignore it: Continuing to drive with a malfunctioning ABS is risky. The sooner you have it addressed, the better.

In short, the engine starting isn't directly related to a security system problem; the ABS light is a separate issue requiring attention.