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How do i check for RPM signal on the dash with out using a scan tool?

The engine will turn over but want start no spark at the spark plugs boots should there be a RPM signal on the dash when cranking? i don't see no signal.

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The tachometer works from the pulse generated for the spark in the ECM or in the ignition control module
the meter is extremely unreliable at cranking speed so at best the needle may flicker at anything under 150 rpms cranking speed
no spark can be from
cam/crank position sensor problems
broken timing belt / chain
ignition control module
run the fault codes to get an idea of the area of failure

Posted on Dec 15, 2016

  • 2 more comments 
  • Joe Russell Dec 15, 2016

    when cranking the tachometer don't move where is the ignition control module located on 2004 GMC Envoy SLT 4.2L how do i test a crank position sensor/cam sensor resistance with multimeter? the battry went dead so i couldn't run the fault codes so i took the battry out and charge it and put the battry back in and then i run the codes it show P2101/P1516/P2119 sometime at the begining of cranking it will spark and stop i notice when cranking after i turn the key loose the starter will keep turning for a few seconds and sometime when cranking i can release the key just a little it act like it want to start. do the crank sensor send a signal to the injectors?

  • Bill Boyd Dec 15, 2016

    gmc have a recall on all vehicles for the last 12 years that involves the ignition switch
    from your description now , trying to start at times , running on when the ignition is released are indications , no spark could all be related to the ignition switch problems and recall.
    the position sensors tell the ECM and the ignition module where the piston is and when the spark is to occur
    the ECM reads parameters from the ignition impulse and then and adjusts the ignition timing like a vacuum advance
    the ECM controls the injectors in 2 ways
    firstly when to squirt ( from the position sensor and how much to squirt from the accelerator position sensor and the heated oxygen sensor
    codes p2101 and p2119 refer to the accelerator position sensor and the throttle position sensor
    at this point in time I would be concentrating on the ignition system / switch and be testing the voltage at key positions
    run should be volts across the switch from the main power wire to the ignition system and power from the switch to the starter relay/solenoid and the ignition circuit in the start position
    get a workshop manual for the vehicle as it has the voltages at sensors when testing and how to test

  • Joe Russell Dec 15, 2016

    where is the the ignition module located where do i get a workshop manual for the vehicle?

  • Bill Boyd Dec 15, 2016

    workshop manuals are available from auto parts shops , technical publication bookshops or e-bay



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1 Answer

How do i use a scan tool to check for RPM when cranking?

Believe you need to plug scan tool into a laptop with the correct software on
Do u have compression as u say u have no spark?

Dec 16, 2016 | Cars & Trucks

2 Answers

New engine in 96 Geo Prizm now not firing

1.6L or 1.8liter engine? Toy 4A or 7A engine?
all 4 cylinder dead. and coil? no spark?
did you hook up all sensors. as the 96 had,(usa car has more)
usa car is OBD2 and runs crank and cam sensors to do misfire detection.(fed law)
any scan tool will tell you why,!
here posted 100 times in ORDER
  1. fuses all good, 12vdc both sides, key on, or its bad.
  2. keyon
  3. CEL lamp in dash turns on, if not ,see #1
  4. plug in scan tool, get comms.? good, pcm talks !
  5. crank for 5 seconds. (least) release key, not off.
  6. SEE Those DTC errors, for spark , cmp,ckp, (P03xx errors)
  7. bingo.? RPM dead cranking? scan tools can see RPM.
  8. sure! my bet by now you found it.

Mar 04, 2015 | 1996 Geo Prizm

2 Answers

How to check a ignition coil pack to see if its good,

the coil does not crank the engine , the starter does that, sorry.
(if you ever had to hand or foot crank and engine , youd under stand that. (like motor cycles or boat engines, or per 30s cars.)

in fact will crank all day with no spark parts on car..

x2, the scan tool does tell you why there is NO STARTS, CRANKS OK. The pcm can detect, one missfire in 10 cmp;ckp signals.
  • release, key
  • scan tool has DTC errors?, read the believe them.
no engine stated of 4 or more,

U checked everything but spark,
why, check spark at all cylinders, all most fire or the engine will not run or stall.
That test be first, if not starting (AFTER SCAN TEST)

IF NO spark fuses are next , not last.
lets do no start fails tests. (cranks perfectly 200 to 300 rpm)
  1. : check fuses
  2. key on, CEL lamp must glow, if not , ECU fuse blown.
  3. crank with scan tool , see P03xx DTC errors, see RPM dead.?
  4. check for spark? got spark x4 or times number of cylinders?
  5. got spark try test fuel now, runs for 3 seconds?
  6. yes, runs on test fuel now means lost fueling
  7. no, dont run on test fuel, means, 1 to 5 done wrong above or engine compression bad.
  8. bad fueling, huge number of tests. check fuel pressure now.
confused, try a shop and watch them, learn.

Jan 12, 2015 | 2005 Suzuki Forenza

1 Answer

Suzuki Aerio 2004, will crank over floods out tho. Changed Plugs and Boots. New baterry too. Can smell gas @ Tail pipe. Wants to fire-but just won't catch. Where do I start looking for the answers.?

what engine? 2.3 or 2.5L?
all cylinders flooding??? spark tips on ALL dripping in gas?
check spark at all spark plugs ( ALL not just ONE)
if spark is good.
this engine is chain cam, so it makes huge noise before death.
did it?, nah
ok, so connect any $9 scan tool, and scan it. (barrow /rent.?)

you crank it for 5 seconds, not less.
and as you crank the scan tool RPM shows 250 to300 rpm and fails to start, the RPM on the tool shows you that the crank sensor is working
now release the key and do not turn off
look for DTC errors. got P0340,355? or any other DTC
that decodes to bad CMP or CKP/
yes, BINGO, the scan tool told you why spark is dead, or way off

the PCM will report Cmp or CKP errors even 1 in 6 pulses.
the PCM runs monitors against these 2 full time. and will see it fail.
and report, it, let it tell why spark is bad.
say spark is good. and still floods.
1: engine compresssion over 150psi? W.O.T?
2: flooding , i pull the fuel pump relay and crank now.
starts and runs for 3 -5 seconds, yes, that is the flood clearing
so i then try test fuel, runs perfect now (no fuel pump) ???
runs for 3 second, each test fuel usage. well good motor, good spark.
what more do you want? sure to run
so you have either insane high fuel pressure. or injectors leaking
can and does happen.
the tests are all in the FSM under injector and pump testing.
i check fuel pressure first. as its a mandatory thing.....
to factory spec. for unsaid engine.
then i do a injector leak down and balance check.
ask if you get this far.....????

Jan 24, 2014 | 2004 Suzuki Aerio

1 Answer

Engine will not start when hot

Difficult to start with hot engine
1. Starter signal circuit.
- Switch off the engine.
- Connect the scan tool, if you have one.
- Switch on the engine (Do not start). Switch on the scanner.
- Select connect/ engine and power-train/ live data/ starter signal.
Note: Different scan tools can have different selection menus.
- Start the engine, watching the starter signal. If it changes from OFF to ON during starting, it is OK. If not then check the ignition switch and wiring for starter signal malfunction.
2. ISC valve circuit.
3. Fuel pump control circuit.
4. Fuel Injectors.
5. Ignition coil (w/ Igniter)
6. Spark plugs gaps.
7. Specific gravity and health of the battery.
8. ECU ground connectors for firm and clean connection to the engine. (Bunch of brown wires with metallic connectors).
9. Starter motor. (250 rpm).
Hope that works and thank you for visiting Fixya.

Jan 21, 2014 | 2004 Toyota Corolla

2 Answers

Engine cranks no start key on engine off rpm reeds 575

i want to buy comma's so bad.
Engine cranks, but it don't start,
with key on,
engine off rpm reeds 575. (im cluesless here)
reads RPM 575 , not running and how pray tell did you
resolve the 5 at the end? what device showed that?
digital tacho or a scan tool? or dash tach? please tell this.

that is a good input , if true. the tacho on many cars is from
the spark primary signal, and if dead the car will not start.
is this a N.American car/ (unstated?)

the first checks (we go from easy to harder, and more tools)
1:got spark?
2: got fueling if spark is good, the ECU cuts fuel if it even suspects bad spark is true.
never look for bad fueling if the ECU reports bad spark.
that takes a scan tool to see what the ECU thinks, and sees.
got a scan tool they only cost $7, here.

If engine compression is at spec. W.O.T.
and spark is good.
then test fuel works all above is good,(mostly), if test fuel works
and it don't start up and stay running, with a fast right foot.
then the fueling system parts are bad.
this works for carb cars or EFI , this part is no different.
old school to new.

see scotty do it.

Sep 26, 2013 | 2004 Suzuki Forenza

1 Answer

No power is produced by ignition coil into the distributor to spark the spark plugs to burn fuel.

what engine, always post the engine. (displacement really helps)
what country?
my guess is G16B engine. with dizzy and not cop coils or packs..
the first steps as always are.:
1: check fuses, with an ohm meter, (some look good and are not)
2: turn on the key,
3: see CEL lamp glow. it must, or ECU lost power.
4: if #3 passes this test, then start car, if car starts and see if CEL goes out, of not it has DTCS to report. get them with any scan tool.
if car does not start (i suspect that is your case? (unsaid,but implied?)
my guess is all 4 spark plugs are dead, right?
then use a scan tool to see if the CMP is working and that RPM moves
to near 300 RPM cranking. if either fail, there will be no spark.
The CMP must pulse or the ECU will never ever make spark.
while cranking said dead motor the ECU can report DTCs related
to the failure if you crank for 5 seconds.
1 fail of CMP in 8 , trips a DTC related .
CMP is in the distrubutor base and DTC means diagnostic trouble codes.

Mar 09, 2013 | 1999 Suzuki Vitara

1 Answer

Replaced bad fuel pump, installed new relay and fuel filter, engine turns over but is not firing on..... positive the fuel pump is pumping gas and checked to see if gas was going thru fuel filter. Tried...

Hi, Ok you have confirmed that it's not a fuel problem. You need to check for spark. Pull the coil wire off of the coil(secondary lead-looks like a spark plug wire) Have some one crank it over and listen for a popping sound. IF yes, spark is at the coil, that means all ignition sensors are working. Next check for spark at ends of wires after cap. IF no replace cap and rotor. IF yes remove a couple spark plugs and check for fouling(wet, fuel etc...) IF yes replace or clean plugs and retest for starting. IF no spark is present at coil you need to scan computer and watch for rpm signal. IF no rpm signal, replace crankshaft sensor with OEM delco part. BIGGEST problem with these engines is Cap and Rotor burn out.

May 23, 2011 | 2002 Chevrolet Blazer

1 Answer

Engine cranks but wont start

Usually if no rpm signal, the vehicle won't start. Engine cranking, did you check for spark at the spark plugs? The fuel pressure you listed may have been the initial prime. It sounds like no injector pulse. The rpm signal comes from crank sensor. If your missing rpm signal, may thought is the crank sensor.
Were there any applicable trouble codes?

Apr 06, 2017 | 2001 Ford F150 Styleside SuperCrew

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