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View Full Version : 1991 honda electrical problems


rockyjb
Feb 20, 2011, 01:30 AM
Problems sometimes it will start and sometimes it won't. When running you can have the lights on but you put on the high beams it will shut the car down. Heater fan does not function at all. Auto seatbelts at times will take forever to go through its cycle and while it is doing that the relay under the center console will start clicking. When you hit the brakes it will kill the engine just like the high beams the gauges will peg at different times. When the turn signals are engaged the speedometer needle will sweep every time the signals click. I have used the phrase "at times" because the problems are intermittent. Not only that but the problems will come and go so you never know what you will be dealing with from day to day. I have a good working knowledge of both mechanical and electrical maintenance on vehicles but this one has me stumped. I have searched for a short and a floating ground extensively and did a half hearted "shake test" on it. In reading some of your diagnostics the computer is looking like it might be the culprit. How do you check the computer other than getting a known good one and swapping it out, can you check it with meters? Any help from anyone would be greatly appreciated. Thanks, rocky

TxGreaseMonkey
Feb 20, 2011, 05:37 AM
The ECM may be intermittently failing.

. Remove and fully charge the battery--most auto parts stores will do this for free.

. Perform the K-Test on the ECM:

The K-Test: Remove the MAP Sensor connector and turn the ignition switch to ON (Position II). Using a multimeter, check for 5 volts going between the MAP Sensor connector's reference wire (+) and ground. As you look at the connector, this is the socket on the right. Really press the black test lead into a cleaned main ECM ground on the thermostat housing. If the voltage is low, it's probably indicating ECM failure. Most failed ECMs will record a fraction of a volt. To me, the K-Test is simple, elegant, and accurate. Many Hondas parked for several years are now back on the road. "The K-Test creates massive value, by providing a low cost solution where one did not previously exist."--TxGM

. Adjust the idle speed to 700 rpm.

. Check the charging system:

https://www.askmehelpdesk.com/cars-trucks/faq-how-troubleshoot-repair-maintain-hondas-selected-other-vehicles-46563-10.html#post1973613