Car stalls after removing the negative terminal off

DO NOT DISCONNECT ANY CABLE WITH THE ENGINE RUNNING!

Every year I did a demonstration on the generator test bench for my students to show what can happen when you do that. It was real easy for the voltage to reach over thirty five volts. That will destroy any computer on the vehicle, the generator's internal diodes and built-in voltage regulator, and any light bulbs that are turned on.

The thinking is that if you disconnect either cable and the engine stays running, the generator must be working but a lot of them will stop working due to the voltage regulator responding to the dips in the "ripple" voltage being produced. That will make a perfectly good generator appear to be bad so that test is not valid.

If a mechanic is caught pulling this stunt he will typically get one verbal warning. For the second offense he will be fired. It is that big a deal.

Some generators respond to the high points in the ripple. That momentary higher voltage goes right back to the field winding and creates a stronger magnetic field. That stronger electromagnet creates a higher output voltage which again creates a stronger electromagnet. It is a vicious circle and voltage can keep on rising until something gives out. The main thing that smooths out that ripple so it does not affect the voltage regulator or the generator is the battery.

Three things are needed to generate the output current. They are a magnet, (electromagnet, in this case), a coil of wire, and most importantly, movement between them. That is why the belt needs to make it spin. One thing that can save you from doing damage by removing a battery cable is not raising engine speed. Generators are relatively inefficient at low engine speeds and their output voltage is less likely to rise to dangerous levels, as long as you do not raise engine speed.

One other thing to keep in mind is batteries give off explosive hydrogen gas. Regardless if your generator is working or not there is going to be a big spark when you remove a battery cable with the engine running. Either the generator's current will be recharging the battery, and that can be up to twenty amps, or the battery is going to be supplying the car's electrical systems, and that can easily be over thirty amps. That kind of current is going to create a big spark when a connection is broken or reconnected. Small arc welders run as low as forty to sixty amps and look at the sparks they create. The reason we do not hear about more battery explosions is because people are careful to not disconnect the cables when there is current flowing through them. It is also why there are huge warning labels on all battery chargers to be sure they are turned off before connecting or disconnecting them from the battery.

Another common generator problem is one defective diode out of the six. You will lose exactly two thirds of the generator's capacity but system voltage will remain normal or it could even be just a little high from the voltage regulator responding to the greatly increased dips in the ripple voltage.

It is always a good idea to wear safety glasses when working around car batteries, but if you still insist on removing a cable while the engine is running, a face shield makes more sense, and have plenty of water on hand to wash any acid off the vehicle's paint.

Ford used to have a really nice generator design that allowed testing right on the back of the unit. Only Chrysler alternators are easier to diagnose. Unfortunately the engineers do not really care about ease of service on GM's and many other brands.

The way you tell if the charging system is working is to measure the battery voltage while the engine is running.. It must be between 13.75 and 14.75 volts. There still could be a bad diode though. You need a professional load tester to test for that. Ripple will be very high and the most output current you will get will be one third of the generator's design value. That is not enough to meet the demands of the electrical system under all conditions so the battery will have to make up the difference, until it runs down.

You did not say what kind of problem you are trying to solve, but removing a battery cable is definitely not the way to "test" anything.

I have a 95 Honda Accord which engine shuts down on own 10-15 secs. after cold start. No hesitation, acts like ignition is turned off. Engine restarts, but will again shut down.

If the dash indicators are not showing when it shuts down, the ignition switch is faulty.

If the stalling is due to excessive low idling speed, you need to get the idling system checked.

If starting is at times difficult after stalling, it would be due to a faulty PGM-FI main relay.

I recently purchased this car and it starts and runs great but on my way home I wanted to set the cruise control so I pressed the on/off button and I the engine shut off and wouldn't start again so I tinkered with it for a while disconnected the battery and it starts right up. My question is what causes the cruise control button to act like a kill switch? And how do I fix that?

I don't see any connection between the cruise control and engine stalling and not restarting.

https://www.2carpros.com/articles/car-cranks-but-wont-start

The next time it fails to start, check go to above link for information how to diagnose the problem.

Hi. I recently bought a '95 2.0l Accord LS, 76k miles. To begin with I had a bit of belt squeal when the weather was cold, so the belt was tightened. Now, for some reason, the engine dies every time I dip the clutch - the revs drop straight to zero. It's getting a little painful as you can imagine. Any ideas what this could be?

Also, the reversing lights do not work. I checked the bulbs and they are fine. All the other tail lights work including fog lamps. Suggestions?

OK, how about that belt you tightened, did the problem occur shortly after that? I suspect a possible problem with the item on the belt you tightened. First, was it the alternator or the power steering? Any noise when idling and giving it gas to stay idling? You may have compounded a problem with the alternator (guessing the alternator belt was tightened) having a bearing that is going out. Tightening the belt puts a lot of pressure on the bearing and it stumbles along at higher rpm but lower rpm it drags the engine down.

Back-up lights, there is a fuse for that, if not that check the wire to the transmission for the switch and it not loose or a bad wire the switch itself could have failed.

Hi. Thanks for the quick response. It was indeed the alternator belt I tightened as I thought this was slipping. When idling, the revs stay at about 2k when first started, but after a little driving they vary between around 500-900 and sometimes plain old 0.

For the lights, I checked the fuses but could not see a specific fuse for reverse lights. Is it called something else? (I need a fuse for my radio power so it'd be handy if that's all it is!)

I assume you read what I said and the questions I asked. I hope you look in to it a bit closer. Back-up is the word for reverse.

Air Conditioning problem
1995 Honda Accord 200,00 miles

Strange question. When it's really hot the air conditioner quits cooling and the car keeps dying while idling. The oil light comes on, but there is plenty of oil in there. Got an oil change, no help. Plenty of coolant, put refrigerant in there. Temp gauge shows that it isn't even close to overheating.

When a/c is off the car doesn't die. In the morning or evening there's no problem because it's not as hot outside.

Any idea what might be going on? We are stumped!

Yes, I did read what you said and thought about it. However, I thought it best to check your terminology. In the UK the average Joe refers to 'Back-up' as reverse. 'Back-up' can suggest an alternative power supply (Back-up power).

I also answered your questions. Any further comments?

Hi hoodleehoo,

What is the idling speed with the A/C turned off?

When the engine did not stall with the A/C turned on, what is the idling speed?

Does the idling speed drops and then move back up when the A/C clutch engages?

Listen to the bearing on that alternator. You could even try loosening it again, just a bit. Good luck!

Thanks for getting back to me! Without a/c idle is about 1150 rpm and with a/c on high about 850 rpm. Mph is hard as it just barely goes over 0 w/o a/c and with a/c about 3/5 that speed.

At 1150 the idling speed is too high. Normal idling speed at operating temperature should be around 700 with or without A/C.

Either the IAC is not working ciorrectly or the valve clearances are too tight.

Get the throttle body and IAC cleaned and retest.
If the idling speed does not increase when engine is started from cold, the Fast Idle Thermal Valve needs to be checked. Ensure all hoses to IAC and FITV are not clogged. Coolant has to run through them to maintain correct IAC operations.

Get the valve clearances checked as well.

Okay. But would the idle being too high cause it to die when the a/c is on? I would have expected being too low to cause it, but not too high.

After cleaning the erg ports. The car is dying out after taking the car for a ride. Check engine light came on and the code was 3, map sensor. Changed the mapp sensor and car is stil dying out. When it feels like its going to die out I pulled the wire out of cylinder 4 and it somewhat have gotten but still not smooth. But once I drive it dies out when I come to a stop. I disconnected the wire from the iac and it shut off. Did a compression test and that came back fine cylinders around 150 each. Also check my other posting and you will see my other issues. I don't know what to do now. Help please

I adjusted the idle to be 700 rpm. Didn't fix the problem. :-/

Check the EGR valve for leakages. If valve is good, disconnet the vacuum hose and retest.

Have the throttle body and IAC cleaned and readjust the idling speed.

Check valve clearances.
Ensure the MAP sensor vacuum hose is connected correctly.

Okay, the IAC seems to be fine. Oddly enough, after allowing it to run for a few minutes the idle seems to be too slow! Maybe that's the problem. It's tightened all the way so we can't make it any faster. :-/

Idling speed should only be adjusted when the engine has reached operating temperature.

Tightening the idle adjust screw would decrease the idling speed and not increase it if I read your comment correctly.

The usual position for the idling speed adjusting screw is about 1/2 to 3/4 turn from fully closed.

If the idling speed is too low, turning on the A/C can cause it to stall but the IAC is computer controlled to compensate the additional load from the compressor and maintain at 700 rpm.

Oops, sorry I was relaying information from my father. It was loosened as much as it will loosen without falling out. lol

Hello folks,
My 95 Honda accord engine died while I was driving down the road - NO RPM, NO SPEED and the engine just died. No check engine light. Recently had the timing belt and water pump changed. Now it won't start, just cranks and won't stay started. I suspect that the Crank Sensor has went bad, but not sure. Before I spend the $165.0 for the parts help me T/S this problem.

Start with the basics, and work your way up, Last tune up was? Wires plugs ALL filters? If all that is ok, check for a stuck EGR, then test fuel pump pressure, If it won't restart, determine what's missing, the engine needs three things to run, Spark at all plugs, gas to all cylinders, and compression in all cylinders, tho an engine may run lacking one in one cylinder, it won't run very well! https://www.2carpros.com/car_repair_video/test_fuel_injection_pressure.htm Go here and checkout our video. https://www.2carpros.com/car_repair_video/test_engine_ignition_system.htm and this one! https://www.2carpros.com/dia/how_to_check_compression.htm Let me know what's missing. To check the sensor: TDC/CKP/CYP SENSOR Page 1 of 1 1.Turn ignition off. Unplug TDC/CKP/CYP sensor connector, located at distributor. Check resistance between terminals "B" and "F", terminals "C" and "G" and terminals "D" and "H". See Fig. 5 . If resistance is 700-1300 ohms (350-700 ohms for Accord F22B2 engine and Odyssey) for each pair, go to next step. If any of resistance is not as specified, replace distributor. 2.Check for continuity between each distributor terminal and chassis ground. If continuity exists at any terminal, replace distributor.

Loosen the screw and pull it out. clean the dirst attached to it.
Remove the air cleaner hose.
Get a can of carb cleaner to spray into the throttle body.
Get a piece of rag to scrub the inner part of the throttle body. Remember to push the throttle plate opened fully, the part that the plate seats on when closed is the most important to be clean.
Spray carb cleaner into the idle adjust screw hole and the 2 other ports inside the throttle body.
Let the carb cleaner soak.
Reinstall the idle adjust screw and back off 1/2 turn from fully tightened. DO NOT force tighten the idle adjust screw.
Retest by starting the engine and allowing to warm up to operating temperature.
Note : Initial starting coud be difficult due to the presence of excessive carb cleaner and the running might be erratic for a short while.

When A/C is turned on, if the idle drops before going back up, remove the 2 holding bolts of the IAC at rear of manifold. Spray carb cleaner into the ports to clear the dirt inside.

HI, I have a 1995 Honda Accord, when it gets up to temperature, the check engine light will come on and the car will die without warning, this all happens at once. Sometimes it will start right back up and sometimes it will take up to half hour, once started it will go anywhere from 5 feet to 20 miles and then die again. I replaced the cadialitic converter and that did not solve this problem, I can not get a diagnostics test run on it because it has no plug in. Please Help!

Thank You,

W. Kipp

Hi W. Kipp, You need an OBD I compliant scanner or diagnostic tester to gain access via the DLC. For manual DTC retrieval, bridge the SCS connector and count the blinks of the CEL with the ignition switch turned on.

My car just off while I was driving to work. It just keeps cranking but will not start. I look through oil filler hole on the valve cover and ask someone to crank it but then I discover the cams shaft are not rotating. ( both the front and back unit) for v6. I checked the timing belt and it is still rigid in place. No sign of it has been broken. Is it possible for the main shaft pulley on which the timing belt get its movement is loose? What else to check?

in the drawing you will see that there are three bolts per cam so probably not that. more than likely the tensioner broke so you may as well pull heads because this is an interference engine and valves have hit the pistons so hard telling what damage has been done.

Will not restart immediately. After setting a while it may restart, or not. After setting longer it will start, and drive normal for weeks or months then it will stall out again for no apparent reason. Have replaced ignition, all fuel filters. Bad fuel has been ruled out as cause. On sixty five mile trip drove fine, sat for six hours and started home. Got seven miles and stalled. Set twenty minutes and started, got one mile and stalled again. Towed to Honda, found nothing wrong, drove home. Next day stalled again. Towed to local Honda, found nothing, (after $600.00). Drove home, got three miles and stalled again. Towed back to Honda, found nothing. Drove home and fine for three months then stalled again. I had the relay mentioned replaced. Problem remains. Mechanic says computer needs replacing. Any ideas?

Hi efinnell, Symptoms are consistent with an intermittently failing PGM-FI main relay. This is a known fault and if you resolder the PGM-FI main relay circuit board, it would work as good if not better than a new one. The cause are broken soldered joints on the circuit board.

I have also seen the ignition distributor cause this issue remove the cap and look for rust colored dust which is a sign the distributor is bad. Please let me know.

Yep, I had this problem as well. The mechanic replaced the distributor and the car has never ran better. Cost me $240.00 but you can find a cheap one at Amazon.

My 1995 2 Door Honda Accord is lowered and has an extra cool air intake ( I bought it like that, I didn't do that to it). I drove through a really deep puddle, not realizing how deep it was, and my car started smoking and then died in the middle of it. I took it to the shop and they said I need a new engine and I'm looking at $5000 for the engine and install. The car only cost $3500! Does the $5000 quote sound right?

Hi skruskol,

Yes, a replacement engine plus labour would cost more than what the car is worth.

It would be more economical to get another car.

the car makes a bad knocking sound from the motor. it starts and runs. the oil and water are fine.but after going about 20 miles the oil light starts flickering and the car wants to die. after it sits for 15-20 minutes it starts rite back up. could my oil filter be my problem?

It sounds like that motor is about gone. With that mileage it's not a surprise and driving it in that condition is just finishing it off.

thank you, any chance that i could possibly rebuild the motor?

It would need too much and wouldn't be worth it. Look for a good used one.

1995 Honda Accord - When I turn on the A/C, the car vibrates really bad until I get to a higher mph but, when I sopt at a light, the car shuts off. What could this be and do I have to do to take care of it? Please help it's 97 degrees here in Georgia.