REGULATOR GP-VACUUM 4P9232 - Caterpillar

Illustration 1. Locations of harness No. 1 and No. 2.2. Use only a 6V3030, 6V7070, or 6V7800 Digital Multi-Meter for this step. At the speed sensor connector, measure the resistance between the sockets, and between the sockets and the housing of the connector. Do not jam the probe tips into the sockets. This can spread the socket and cause a poor connection.First, use the 20 MegOhm scale for each measurement. If the reading is less than 0.02 MegOhms (20,000 Ohms), switch to the 20 k Ohms scale for the final reading. Do not touch the probe tips when making measurements on the 20 MegOhms scale because the reading will be affected.
3. The locations of the sockets are shown in Illustration 2. Record the readings as follows: Socket A to Socket C OhmsSocket B to Socket C OhmsSocket A to Socket B OhmsSocket A to housing OhmsSocket C to housing Ohms
Illustration 2. Location of sockets in the harness connector for the speed sensor.4. With a good harness, all the measurements should be over 20 MegOhms (20 MegOhms = 20 million Ohms). The meter will read "OL" in this case.Any resistance less than 20 k Ohms (20,000 Ohms) indicates a contaminated or damaged harness. Contamination can cause varying resistances from one day to the next, as moisture soaks into the contamination and then evaporates from it. Most harness contamination will be in the back of the speed sensor connector, due to imperfect potting. There is no way to clean or seal a contaminated harness. The speed sensor may not provide a valid signal if the resistance from C to B, or from C to the housing, is less than about 3 k Ohms (3,000 Ohms). The other resistances are not as critical, but any resistance below 20 k Ohms indicates serious contamination which can cause a malfunction if more moisture enters the harness.
5. If unacceptable low resistance is found, disconnect harness No. 1 from harness No. 2, and test again to confirm which harness has the problem.If the problem is in the speed sensor connector on harness No. 1, this connector can be cut off and replaced with the 8T8666 Connector Kit. Use Special Instruction SEHS8618 included in the Kit.
If the problem is in harness No. 2, replace this harness assembly.