Wiring Harness (Short Circuit) - Test
短路是一种可以导致电流高于期望值的电路故障。 通常，短路是指绕过负载电路。 指示灯电路导线之间短路会在导线中产生过大电流，但指示灯上却没有电流。 指示灯短路。 正常电路中的电阻值可能会发生变化，但是特定电路与其他无关电路之间的电阻值始终大于 5K Ω。 下述步骤将说明短路测试：
参考: 有关完整的电气示意图，参考正在维修的机器的电气系统示意图。
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| 故障诊断与排除测试步骤 | 数值 | 结果 |
|---|---|---|
| 1. 确定短路。 A. 确定可疑电路中的接头和导线编号。 使用机器的电气系统示意图检查电路。 B. 将钥匙起动开关和断路开关转到断开位置。 C. 从配线线束上断开部件和 ECM。 D. 在 ECM 机器线束接头上，将一支万用表表笔放在可疑导线的触点上。 E. 使用另一支万用表表笔检查 ECM 接头中的所有其它触点与机架接地之间的电阻。 |
所有电阻读数均大于 5K Ω。 |
正常 - 线束电路正常。 停止。 不正常 - 电阻小于 5 Ω。 机器线束中存在短路。 可疑导线与具有最低电阻测量值的导线之间短路。 修理：修理或更换机器线束。 注：电阻大于 5 Ω 但小于 5K Ω 表示电路中的连接松动或腐蚀。 电阻测量值大于 5K Ω 表示电路中存在开路。 停止。 |
Caterpillar Information System:
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