At Ask Me Help Desk you can ask questions in any topic and have them
answered for free by our experts. To ask questions or participate in
answering them you must register for a free account. By registering you
will be able to:
Get free answers from experts in any of our 300+
topics.
FAQ: How to Troubleshoot, Repair & Maintain Hondas and Selected Other Vehicles
Check out these tips and explanations from our Cars & Trucks expert--the best car and truck guy on the net!
Of course, you're also welcome to post questions to this board for more information: Just click the "Ask about Cars & Trucks" button (NOT the Answer this Question button) at the top of the page. Be sure, though, to check the list below to see if your issue is already covered.
Members: Please do not post replies in this thread. If you have a question, click on the Ask About Cars & Trucks button above.
. Ensure the battery is fully charged, before diagnosing starter problems.
. Ensure the gearshift is in Neutral or Park (automatic transmission), or the clutch pedal is depressed (manual transmission), if the starter motor does not turn at all when the switch is turned to Start.
1. If the starter motor doesn't turn, but the starter solenoid (relay) "clicks" when the ignition switch is turned to Start, the problem is with the battery, starter solenoid, or starter motor connections.
2. Disconnecting the negative battery cable first, clean battery terminals and cable connections with a battery terminal brush, No. 240 abrasive cloth, or steel wool. Also, check the battery ground cable connection to the body and engine. Apply silicone dielectric grease, when finished.
3. While the negative battery cable is disconnected, clean starter motor and starter solenoid connections. Apply silicone dielectric grease, when finished. Make sure all connections are secure. When installing the starter cable, make sure that the crimped side of the ring terminal is facing out. Reconnect the negative battery terminal last.
4. If the starter motor spins but the engine is not cranking, the overrunning clutch in the starter motor is slipping and the starter motor must be replaced. Also, the ring gear on the flywheel or drive plate may be worn.
5. If the solenoid plunger cannot be heard when the switch is actuated, the battery is bad, the fusible link is burned (circuit is open), or the solenoid is defective.
6. In order to check the solenoid, put the transmission in Park and remove the push-on connector from the solenoid “S” terminal. Connect a jumper lead (12 AWG), or preferably a remote starter switch, between the positive battery terminal and the exposed “S” terminal on the solenoid. If the starter motor now operates, the solenoid is fine and the problem is with the ignition switch, neutral start switch, or wiring. If the starter motor still does not operate, replace the solenoid.
7. If the starter motor cranks the engine slowly, ensure the battery is fully charged and all terminal connections are clean and tight. Then, check connections at the starter solenoid and battery ground. The engine will also crank slowly, if it’s partially seized or has the wrong viscosity oil in it. Synthetic engine oil allows starter motors to turn the engine over easier and faster, thus promoting starting and reducing battery drain.
Nerdy Bonus:
Ohm's Law states Amperage = Volts/Resistance. As resistance doubles, amperage is cut in half. Resistance is increased by corrosion, smaller cable size, poor cable material, and heat. Electric motors (e.g., starter motor armatures) will have greater impediance and generate less torque when they are hot.
Taking this a step further, focus on corrosion and cable size. Smaller cables and corrosion greatly reduce the effective cross-sectional area of grounds. Based on the formula Area of a Circle = Pi x R-squared, as the effective cross-sectional area of a cable gets cut in half, the resistance goes up four fold. This means that the amperage available to the starter motor would be 1/4 of what it would be otherwise, when you plug these values into Ohm's Law. That's why all of these factors influence starter motor performance, especially when they are failing.
Most engine overheating problems are directly attributable to poor preventive maintenance. Attention to detail makes a big difference. It's best to change coolant every 3 years with a 50/50 mixture of auto maker recommended antifreeze and distilled water. It's good practice to remove engine drain plugs during this process. Today, it's important to only use the antifreeze recommended by the car's manufacturer. There are huge differences in the types of antifreeze and using the wrong one can have disastrous consequences. Don't take a chance and use the wrong antifreeze. Honda recommends using an antifreeze that doesn't contain silicates or borates. Silicates are abrasive and cause premature water pump bearing seal wear, which greatly shortens the life of the bearing. Once antifreeze gets into the bearing, it will not last long.
It's also important to use distilled water, because tap, well, and softened water can cause unforeseen problems. Tap and well water are loaded with minerals that can build-up and block radiator and heating cores. Minerals found in tap water tend to combine with coolant additives. When this happens, they form a chemical complex called “phosphate scale,” which coats the heat-transfer surfaces of radiators, heater cores, and heads, resulting in decreased heat-transfer efficiency. When this occurs, your vehicle will overheat and run much hotter than it was designed to. This scale can also lead to the destruction of water pump bearings. When this happens, the radiator or heater core must be removed and roded or replaced. Soft water is known to weaken solder joints and cause corrosion, due to salts in the water. Keep in mind that chemical reactions increase with temperature. With the high heat of modern engines, it doesn't take long for caustic steam and heat to corrode, overheat, and damage an aluminum block engine not properly maintained.
It's also important to regularly change radiator and heater hoses. Most experts recommend changing all hoses every 4 to 7 years. Inspect hoses regularly for softness, bulges, and deterioration. Pay particular attention to the top radiator hose. Internal deterioration may be almost impossible to detect. Therefore, don't be "penny wise and pound foolish" and try pushing things too far. Many aluminum heads and valve trains have had to be replaced, due to hose failure. The repair bill can easily be $2,300 or more. All it takes is allowing an aluminum head engine to overheat once. Never drive a car that is overheating--have it towed.
Common causes of overheating:
1. Insufficient coolant.
2. Radiator core blocked--mineral build-up (phosphate scale) and corrosion are the most common causes.
3. Faulty thermostat--sticking closed. Incorrectly installed thermostats is one of the leading causes of Hondas overheating.
5. Inoperative water pump--pinch the top radiator hose closed with your hand, while the engine is idling, then release it. You should be able to feel a surge of coolant, if the pump is working properly. Change the water pump every time you change the timing belt.
6. Deteriorated/damaged hoses.
7. Cooling fan not operating properly--check the Engine Coolant Temperature (ECT) Switch, not the ECT Sensor. Cooling fans not operating properly is one of the most common reasons Hondas overheat.
8. Improper grade of engine oil--higher viscosity oil generates more internal friction and heat. Synthetic engine oils have higher coefficients of heat than conventional oils, which allows bearings and engines to run cooler.
Parasitic battery drain is the cumulative load produced by electrical devices (e.g., ECMs, clocks, security alarms, and radio presets), when the ignition is turned off. These items continue to operate, when the ignition has been switched off, and are becoming an ever increasing problem. Normal parasitic loads are below 75 milliamps (.075 amps). When parasitic load is greater than 75 milliamps, batteries will drain even faster. Glove box, trunk, and under hood lights that do not automatically turn off when the door is closed, or shorted alternator diodes, are common offenders. Cooling fans, power seat belt retractors, radios and dome lights left on, alarm systems, and electric car antennas can also cause batteries to drain overnight. Leaving headlights on will usually discharge a fully charged car battery, with 90 minutes of reserve capacity (36 amp hours), in a couple of hours.
Two methods are used to test for parasitic load (engine off, under hood light disconnected, accessories off, and vehicle doors closed):
1. The basic approach is to connect a 12-volt bulb across the positive and negative battery terminals to test the bulb and battery. If it glows brightly, remove the negative battery cable and connect the bulb in series between the negative battery cable connector and the negative battery terminal. If the bulb continues to glow brightly, start removing fuses or connections to the positive battery, one-at-a-time, until the offending electrical component is identified by the bulb dimming.
2. The best approach is to use a DC ammeter, connected in series between the negative battery cable connector and the negative battery terminal, or a clamp meter (set to DC amps), clamped around the negative battery cable. Starting with the highest scale (or set multimeter to auto range), determine current load. If load is above 75 milliamps, after the initial surge, start removing fuses or connections to the positive battery post, one-at-a-time, until the offending electrical component is identified by the parasitic load dropping to 75 milliamps.
01--30 A, Moonroof motor
02--Not used
03--7.5 A, Integrated control unit, Ceiling light
04--20 A, Right rear power window motor
05--20 A, Driver's power window motor
06--20 A, Power door lock control unit
07--20 A, Left rear power window motor
08--20 A, Front passenger's power window motor
09--10 A, Right headlight (High beam)
10--10 A, Left headlight (High beam, High beam indicator light)
11--Not used
*12--15 A, ECM, Cruise control unit, Alternator
[This is the crucial ACG (ALT) (S) fuse I frequently refer to, if your Civic does not have the Supplemental Restraint System. If missing, or blown, the CEL will not go out and the car will not start, since it controls power to main relay terminal 5. Terminal 5 controls power to the main relay's first relay, which controls power to the ECM and fuel pump. If terminal 5 doesn't receive power, this relay won't "click," when the ignition switch is turned to ON or Position II.]
13--7.5 A, Rear window defogger system, ABS control unit, Power mirror actuator
14--20 A, Wipers/washers system, Moonroof relays
15--10 A, Gauge and indicator lights, Clock
16--7.5 A, Daytime running lights control unit (Canada)
17--10 A, Daytime running lights control unit (Canada)
18--7.5 A, ECM, PGM-FI main relay
19--10 A, Dash lights, Taillights, Parking lights
20--Not used
21--10 A, Right headlight (Low beam)
22--10 A, Left headlight (Low beam)
23--15 A, Stereo radio/cassette player
*24--15 A, SRS unit (VB)--Red wire.
*24--15 A, ECM, Cruise control unit, Alternator--BLK/YEL wire to main relay.
[This is the crucial ACG (ALT) (S) fuse I frequently refer to, if your Civic has the Supplemental Restraint System. If missing, or blown, the CEL will not go out and the car will not start, since it controls power to main relay terminal 5. Terminal 5 controls power to the main relay's first relay, which controls power to the ECM and fuel pump. If terminal 5 doesn't receive power, this relay won't "click," when the ignition switch is turned to ON or Position II.]
*25--10 A, SRS unit (VA)
__________________
*12: Under-dash fuse/relay box (Without SRS)
*24: SRS fuse block (With SRS)
*25: SRS fuse block (With SRS)
2. Relays
Starter Cut Relay (M/T)
Power Window Relay
B. Under-Hood Fuse/Relay Box
1. Fuses:
31--15 A, PGM-FI main relay
32--7.5 A, ECM, Clock, Radio/cassette player
33--15 A, Radiator fan motor (Via radiator fan relay)
34--30 A, Rear window defogger (Via rear window defogger relay)
35--20 A, Condenser fan motor, A/C compressor clutch
36--50 A, To under-dash fuse/relay box (No. 1/No. 3/No. 6 fuses and power window relay
37--30 A, Blower motor (Via blower motor relay)
38--Not used
39--50 A, To ignition switch (BAT)
40--40 A, To combination light switch and No. 17 fuse
41--80 A, Power distribution
42--20 A, Horn system, Brake system, Key interlock solenoid
43--10 A, Hazard warning light, Turn signal/hazard relay
44--Not used
45--Not used
46--Not used
Under-Hood ABS Fuse/Relay Box (Sedan):
51--50 A, ABS motor (Via ABS motor relay)
52--Not used
53--Not used
54--15 A, ABS control unit (+B2)
55--20 A, ABS control unit (+B1, +B3)
56--Not used
57--7.5 A, ABS control unit
58--Not used
2. Relays:
Radiator (Cooling) Fan Motor Relay--Connected to Fuse No. 33
Rear Window Defogger (Defroster) Relay--Connected to Fuse No. 34
Heater Blower Motor Relay--Connected to Fuse No. 37
ABS Motor Relay
ABS Rear Fail-Safe Relay
ABS Front Fail-Safe Relay
____________________
^For 1993 Honda Civics. Information may or may not be applicable to other year Civics.
1. Multimeter. Set multimeter to DCV, turn ignition switch to ON (Position II), touch the black test lead to ground, and touch the red test lead, in turn, to each test point on the fuse. The meter should record 12+ volts. Voltage must be recorded at each test point on a fuse; otherwise, the fuse is bad.
An alternative method, which is very fast, is to set your multimeter to audible ohms, DISCONNECT THE NEGATIVE BATTERY TERMINAL (or you could blow the fuse in the multimeter), and touch the red and black test leads to the test points on each fuse. When you hear the meter buzz, you know the fuse is good. This is my favorite method. If your meter doesn't have audible ohms, but it does have ohms, you can still use this method--just read the meter instead. The alternative methods perform a continuity test on the fuse. Just remember to de-energize the circuits, by disconnecting the negative battery terminal, and record any radio activation codes first.
2. Test Light. Turn ignition switch to ON (Position II), connect alligator clip to vehicle ground, and touch the probe to each test point on the fuse. The test light must come on at each test point on a fuse; otherwise, the fuse is bad.
These methods allow you to accurately and quickly check all under-hood and under-dash fuses in several minutes, even in dark, cramped locations. They eliminate the possibility of removing and replacing the fuse in the wrong slot. Should a fuse test bad, use the fuse puller, provided in the under-dash fuse/relay box, to remove it.
Important Note: Due to corrosion, it's not uncommon for fuses to be good but not pass current, particularly in trucks. In this situation, clean the fuse's contacts with No. 240 abrasive cloth, or steel wool, and lightly coat with dielectric grease. Ensure fuse boxes are "Military Ready" for any environment.
Honda automatic transmissions are equipped with the following devices to prevent inadvertent shifting:
. Automatic transmission selector with shift lock.
. Key cylinder with interlocked ignition key.
Shift Lock System:
The shift lock system prevents the shift lever from moving to Reverse or D4 from the Park position, unless the brake pedal is depressed and the accelerator is in its rest position.
Note:
. The shift lever cannot be shifted when the brake pedal and the accelerator are stepped on at the same time.
. In case of system malfunction, the shift lever can be released by pushing a key into the release slot near the shift lever.
Key Interlock System:
The ignition key cannot be removed from the ignition switch, unless the shift lever is in Park. When the shift lever is in any position other than Park, a solenoid is activated, making it impossible for the key to be removed, until the shift lever is moved to Park.
Troubleshooting:
If you are experiencing problems, particularly in cold weather, check for a faulty automatic transmission gear position switch (most likely). Next, check for a possible faulty steering lock assembly (key interlock solenoid and key interlock switch). See section K.
Automatic Transmission Gear Position Switch Replacement
1. Remove console and disconnect 14-P connector from switch.
2. Remove both console switch mounting nuts.
3. Position switch slider to "Neutral."
4. Move shift lever to "Neutral," then slip switch into position.
5. Attach switch with both nuts.
6. Test switch in Park and Neutral positions of shift lever. Engine should start, when shift lever is in Neutral (anywhere in the range of free play).
7. Connect 14-P connector, clamp harness, and install console.
Also, take a test light or multimeter and check all under hood and under dash fuses. These fuses can affect power going to the 8-P connector and the interlock control unit. Check for good contact between the connector and socket terminals. If the problem remains, you may want to replace the interlock control unit, which is located near the left kick panel (close to the main relay). These are sophisticated systems that can sometimes challenge the best technicians.
When the engine is cold, the air conditioner compressor is on, the transmission is in gear (automatic transmission only) or the alternator is charging, the ECM controls current to the Idle Air Control (IAC) Valve to maintain correct idle speed. Here’s an overview of how the PGM-FI System works.
Background
Various inputs to the ECM are TDC/CKP/CYP Sensor, MAP Sensor, ECT Sensor, IAT Sensor, TP Sensor, HO2S, VSS, BARO Sensor, EGR Valve Lift Sensor, Starter Signal, Alternator FR Signal, Air Conditioning Signal, Automatic Transmission Shift Position Signal, Battery Voltage (Ignition 1) Brake Switch Signal, PSP Switch Signal, ELD, and VTEC Pressure Switch.
Inputs are received and processed by the ECM's Fuel Injector Timing and Duration, Electronic Idle Control, Other Control Functions, Ignition Timing Control, and ECM Back-up Functions. These are the primary functional areas within the ECM.
Outputs from the ECM control Fuel Injectors, PGM-FI Main Relay (Fuel Pump), MIL (Check Engine Light), Idle Air Control (IAC) Valve, A/C Compressor Clutch Relay, Ignition Control Module (ICM), EVAP Purge Control Solenoid Valve, HO2S Heater, EGR Control Solenoid Valve, Alternator, Lock-up Solenoid Valve A/B (A/T), VTEC Solenoid Valve, and Interlock Control Unit.
Idle RPM
Once you understand how the PGM-FI system is configured, it’s easy to see how the ECM, Idle Air Control Valve, and the Ignition Control Module affect idle rpm. If the ECM’s Electronic Idle Control function is not working properly, then it cannot properly control the IAC Valve. Likewise, if the ECM’s Ignition Timing Control function is not operating properly, it cannot properly control the ICM (ignitor). Obviously, idle rpm will also be affected if there’s a problem with the IAC Valve or the ICM. As stated above, the ECM controls current to the Idle Air Control (IAC) Valve to maintain correct idle speed. This cannot happen if the IAC Valve is failing. The same situation exists if the ICM is failing. The ECM will tell the ICM to open and close the primary voltage circuit going to the coil and it won’t respond properly. The result will be erratic spark plug firing and erratic rpm.
Conclusion
If you are experiencing erratic idle rpm, try and isolate whether the problem is caused by the ICM (ignitor), IAC Valve, or the ECM. My experience has been that a failing ICM is usually responsible for the problem. Keep in mind that tachometers are connected directly to the ICM. Therefore, a fluctuating tachometer needle is often a dead giveaway. Heat and poor preventive maintenance (causing high secondary voltage to be discharge on internal distributor components) frequently causes the ICM (and coil) to fail. Besides performance, this is another reason why it's important to regularly replace spark plugs, spark plug wires, rotors, and distributor caps. Electricity will always follow the path of least resistance, even if it isn't the intended one. Our job is to ensure the intended path is the path of least resistance.
Our cold weather friends, living in places like Alaska, Canada, Northern Europe, and the Baltics, who are experiencing insufficient heat during the winter, may want to restrict the airflow through the radiator, by carefully rigging a plastic radiator cover (winter front). You may have to experiment with the proper size--better yet, make it adjustable. This is not an uncommon problem, during the winter, on some vehicles. I'm sure you have seen folding mechanical radiator covers on some delivery trucks. Your heater core, when the blower is turned on high, may be acting like an efficient radiator and dropping the engine temperature too much (hyper cooling). A simple "winter front" could make a big difference in your driving comfort, performance, and gas mileage.
Linear Mode
