GM Prizm/Nova 1985-1993 Repair Guide

Fuses

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See Figures 1 and 2



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Fig. Fig. 1: Use the fuse puller to remove the fuse. Do not twist the fuse when removing.



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Fig. Fig. 2: A blown fuse (left) compared with an intact fuse. The fuse cannot be inspected without removing it from the fusebox

Each fuse location is labeled on the fuseblock identifying its primary circuit, but designations such as Engine, CDS Fan or ECU-B may not tell you what you need to know. A fuse can control more than one circuit, so check related fuses. As an example, you'll find the Prizm cruise control drawing its power through the fuse labeled ECM-IG. (This sharing of fuses is necessary to conserve space and wiring; if each circuit had its own fuse, the fuse box would be the size of the trunk lid.)

The individual fuses are of the plastic or slip-fuse type. They connect into the fusebox with 2 small blades, similar to a household wall plug. Removing the fuse with the fingers can be difficult; there isn't a lot to grab onto. For this reason, the fusebox contains a small plastic fuse remover which can be clipped over the back of the fuse and used as a handle to pull it free.

Once the fuse is out, view the fusible element through the clear plastic of the fuse case. An intact fuse will show a continuous horseshoe-shaped wire within the plastic. This element simply connects one blade with the other; if it's intact, power can pass. If the fuse is blown, the link inside the fuse will show a break, possibly accompanied by a small black mark. This shows that the link broke when the electrical current exceeded the wires ability to carry it.

It is possible for the link to become weakened (from age or vibration) without breaking. In this case, the fuse will look good but fail to pass the proper amount of current, causing some electrical item to not work.

Once removed, any fuse may be checked for continuity with an ohmmeter. A reliable general rule is to always replace a suspect fuse with a new one. So doing eliminates one variable in the diagnostic path and may cure the problem outright. Remember, however, that a blown fuse is rarely the cause of a problem; the fuse is opening to protect the circuit from some other malfunction either in the wiring or the component itself. Always replace a fuse or other electrical component with one of equal amperage rating; NEVER increase the ampere rating of the circuit. The number on the back of the fuse body (5, 7.5, 10, 15 ,etc.) indicates the rated amperage of the fuse.

 
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