remote start keeps grinding or shuts off

My starter keeps cranking for a little bit after the engine is started or sometimes shuts off and the starter tries again. I have tried to program my starter with the RPM signal settings. and sometimes I can get it to stay on, but it sounds like something is still grinding for a few seconds after the car is started which doesn't happen with the key start. The grinding could be from something else, it doesnt sound like the crank sound from the key.

I used an oscilloscope to see the tach signal, which was a constant amplitude and just changed frequency by increasing the RPM of the engine. So im pretty sure its giving good info. Its about 7V pk-pk but is not perfectly square.

What am I doing wrong?

More info is needed - what year/make/model is your car?  What did you install in it?

You say 7v pk-pk would that be 0-7vdc or -3.5- +3.5vdc?

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Kevin Pierson

Sorry, its a 2000 toyota camry

Remote start is Avital 4001

7v pk-pk is -3.5 - +3.5

When i remote start, the car starts and cranks and it seems fine, but after the crank stops going, i hear a clicking/grinding sound for a few sec and then it dissapears.

Ocasionally after the car is started, the remote start will also shut the car off and then try again. It thinks i guess the car didnt start right, but its running...

I have been able to get the RS to set with the tach signal to keep the car on, but it seems random when I program it multiple times.

My major concern is the clicking/grinding noise which doesnt occur when I use the ignition key.

I would use a different tach reference - like a fuel injector.

The problem you are having is definately a sign that the tach signal isn't being read reliably.  Remote starts, since they are grounded to the battery, arn't capable of reading (-) voltages so your signal, to the remote start unit, becomes a (almost perfect) square wave with a 3.5vdc potential.  In theory 3.5vdc should be enough voltage to trigger the RPM input on the unit, but it obviously isn't.

When you say the wave is "not perfectly square" what does that mean?  Are there some quick pulses at the beginning or end?  That could also be why you are having issues - especially if the unit averages pulses.  Also, is the signal repeatable or does it have an abnormal signal back (like a crank or cam angle sensor would).

By going with a fuel injector you'll have a cleaner signal that will switch between 12vdc and ground and the remote start unit should have no problems reading that. 

The only other thing I can think to try is replacing the brain - maybe there is something damaged causing it to intermittenly screw up.

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Kevin Pierson

OK I will try to look for another one.
Yesterday I tried to remote start the car and it started and stayed on. After i got home(1 hour drive) I turned it off and remote started it again and it would start and shut off and try again. I didn't change any settings.

Does this sound like what you were refering to, a week tach signal. I just want to make sure, because it was a pain to find and wire.

Almost any time a remote start system tries to crank the starter while the car is already running it is a tach related issue.  If the car starts and shuts off right away it could be a factory security issue or a tach issue.  However, since you said the car would start and stay on and recrank that is why, to me, it sounds like a tach issue.

Tach wires shouldn't be hard to find, just find a fuel injector and follow the wiring.  Tach wires may be hard to get to, but they shouldn't be hard to find.

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Kevin Pierson

Ok i tried a tach wire that was right off the engine, and it was abot 1V pk-pk AC. I dont know why this wire was not as strong but in the end, it did not help stop the starter from clicking.

Is there a way i can get a signal amplifer to maybe see if that is the issue?

use a fuel injector.

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Kevin Pierson

Does this vehicle have a small black box, mounted on the front wheel arch which cables up to the injectors, if so open it and you will find some excess RED / black cable. This is one tach take off also on some Toyota/Lexus models, the OBD socket under dash, black with silver dots, also back of rev counter(tacho), on instrument panel, follow printed circuit.  Incidentally on a car that age, take an LED tester or just a 12volt LED, one side to ground.  MAC do a very good one part number something 120, will flash the LED faster as you increase the revs, works every time, quick and efficient.

KPierson
Thankyou, I used this description

"NOTE *3 on the 4-Cylinder engine the BLACK wire is in a GRAY CONNECTOR located on the COIL, drivers side of the engine, on the V-6 use the GRAY wire located at the IGNITOR, located just in FRONT of the STRUT TOWER."

I am assuming this is the wire off the fuel injector, am i mistaken?

Howie II
Thankyou, I will try to look for thoes wires, there is a small black box with fueses. I will try the LED trick.

What do you mean by..."MAC do a very good one part number something 120"

MAC do a tester which has pos and neg inputs via croc clips, a probe and  a red and gren LED as the display. Probing a pos source will light the red, neg the green. Pr4obing the half wave tach source will keep one on constant, the other will flicker. I have been using one for years to find tach and it has never failed me.

If the wires are connected to the coil then they arn't fuel injectors.  Coils are associated with spark plugs and use a variety of different methods to control them.

Fuel injectors, for the most part, are simple on/off devices that pulse one time per two complete crank revolutions (in a 4 stroke motor). 

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Kevin Pierson

KPierson
Ok I will look again for the fuel injector wire...in the mean time I took snapshots of the two places I am taping the tach signal from...

howie II
I looked at the balck/grey dot wire on the OBD connector with my scope and did not see a tach signal. I will look for the RED / black under the hood next.

Below are my scope images of idle engine, tach wire.
It seems that the starter keeps turning untill it reaches this rest/idle point. I tried to set the tach so that it uses a higher frequency point by keepin my foot pressed on the gas at a constant freq, but then the car would never stay on. It would shut off and try agian.
Wire off ECM, 13Hz

Wire off grey connector, 11.5Hz

<a href='https://www.mediafire.com/?imdw3t2minz'>https://www.mediafire.com/?imdw3t2minz</a>

Sorry thoes images didnt work, here is there links, disreagard the above post
Wire off ECM, 13Hz
https://www.mediafire.com/file/imdw3t2minz/ECM_tach,13Hz.JPG
Wire off grey connector, 11.5Hz
https://www.mediafire.com/file/yg0qqzf4mjw/Engine_tach,11'5Hz.JPG

You don't want a HIGHER frequency, you need a LOWER frequency. 

Like I said a while ago - when the starter continues to crank what happens if you blip the throttle?  You never answered that question.

Another thing to try is to wait until the car is warm and the idle RPMs drop - then reprogram the tach signal. 

As long as the 11.5hz or 13hz signal has enough voltage potential for the remote start to distinguish between ON and OFF they "should" work.  That is roughly the frequency of a pulse every other crank revolution.

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Kevin Pierson

KPierson
Thankyou for your help, and sorry for taking up to much of your time.
I still dont see where you aked me to "blip" the throttle, but sorry for dodgeing that Q. I finally found a fuel injector, and fallowed the wire back to the ECM and taped it from there.

VOLLA! the f'n peice works! Perfectly! I scoped that signal, and it was about 6V AC pk-pk. I dont know why the other signals didnt work but thats all behind me now.

As to lower frequency, the car starts and the rpm is at about 1200 and then idles to about 900. This is why I though if I could get a higher frequency correlating to 1200, it would stop trying to crank earlier and not wait for it to reach idle. What am i thinking wrong here, out of curriosity?



howie II
Thankyou for your help, the BLACK/ grey dot wire was not a tach signal on the OBD connector and i could not find the BLACK/ red wire in the engine compartment you spoke of. Thankyou for your efforts tho.



FOR REFRENCE...
the wires i used were located on the ECM on the plug at the very bottom behind the glovebox. There is a black wire with the tach signal that was too week. Off the fuel injectors, I saw that each injector had a BLACK/ red wire and then the 4 cylinders(V4) each had unique color. I am assuming the BLACK/ red was ground. The 4 other wires were BLUE,RED,WHITE,YELLOW. I just found this combination on the ECM plugs, and the were a lower gauge then the other wire and all right next to each other. They were on the same plug I tapped the black tach wire off of. This was for a 2000 Toyota Camry V4.

When I say "blip" the throttle I meant just tap it and rev the car to 2500-3000 rpm and see if the higher rpm shut the crank output off.

A starter cranks a car at around 250 RPM, so once the motor has reached at least 900 rpm it can be deduced that the motor is running on its own.  So, you want to program the tach to the lowest possible RPM that the car will run at at idle.  It sounds like the car was starting but the tach frequency was programmed TOO HIGH and the motor wasn't consistenly hitting that RPM so the starter kept cranking.  So, to fix this you would want to program the tach LOWER.  One way to test and verify this is to "blip" the throttle when the starter is staying engaged and see if the higher RPM shut the crank output off.

The fuel injector should be 0-12vdc.  The BLACK/ red wire should actually be fused 12vdc and the four different color wires should be (-) outputs from the ECU.

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Kevin Pierson

Maybe you guys could help me with the problem i'm having. I had some custom units made for me. The problem is first time it starts it runs fine, if we flood the engine and kill it and when it tries to do a restart it will run for 10 seconds and shutoff and not try to restart. We had them do custom hz for the tach signal. they are 10hz and 30hz.. Somehow could it be shutting down due to the lower frequency being to high on a restart. Were using an injector as a tach signal.

flybyu wrote:

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I had some custom units made for me.

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It maybe impossible to diagnose, without a design and wiring schematic.

flybyu wrote:

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it will run for 10 seconds and shutoff and not try to restart.

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• Does the vehicle rev high, while in this scenario? Depending if/on how over-rev protection was designed in, that may be a cause.
• Does the igntion stay active, while in this scenario? If so, the tach source may not be recognized properly.

Honestly, I'm shooting in the breeze, without a known platform.

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Ideal - cmon dude, add to topics in a useful manner, not stuff that is obvious.
Story - Phzzzt! Hey, what happened?! ... Isn't it obvious?
Moral - Never dismiss the obvious.