93 Grand Cherokee Ignition Question
08-28-2005, 12:41 AM
#11
Guest
Posts: n/a
Re: 93 Grand Cherokee Ignition Question
On Sat, 27 Aug 2005 22:12:03 UTC Chuck <chuck@westmichigan.null>
wrote:
> I thought the sensors too. The CrankshaftPS ohmed out infinite with a
> Fluke digital meter. I also checked all the fuses and swapped around
> relays to eliminate this.
Ohmic check of the CPS is a waste of time unless you do it right - it
is a Hall Effect switch which is basically a transistor that is turned
on by the change in the flux field. You may get some info if you make
all your measurements the repeat with reversed leads. This causes some
"0" readings to go to open while other open leads will indicate a
small current flow. The only reliable way to measure it is with a
scope while it's under power, altho some better digital VOLTMETERS
(not OHMETERS) have a fast enough response time to show whether it is
actually pulsing or not. An older analog VOM will also work to check
the voltage.
--
Will Honea
wrote:
> I thought the sensors too. The CrankshaftPS ohmed out infinite with a
> Fluke digital meter. I also checked all the fuses and swapped around
> relays to eliminate this.
Ohmic check of the CPS is a waste of time unless you do it right - it
is a Hall Effect switch which is basically a transistor that is turned
on by the change in the flux field. You may get some info if you make
all your measurements the repeat with reversed leads. This causes some
"0" readings to go to open while other open leads will indicate a
small current flow. The only reliable way to measure it is with a
scope while it's under power, altho some better digital VOLTMETERS
(not OHMETERS) have a fast enough response time to show whether it is
actually pulsing or not. An older analog VOM will also work to check
the voltage.
--
Will Honea
08-28-2005, 08:28 AM
#12
Guest
Posts: n/a
Re: 93 Grand Cherokee Ignition Question
On 2005-08-27, DougW <post.replies@invalid.address> wrote:
> Chuck did pass the time by typing:
>> My kid's Jeep now starts and run for 1-2 seconds, then stalls. I checked
>> the ohms on the CPS and it's infinite as be between 2-3 pins. I also
>> check the TPS voltage and fuel pressure and both were fine. The fuel
>> pressure doesn't drop when the engine cuts out. I'm not sure if the
>> injectors are shuting down cutting off fuel or the spark is quitting, or
>> both.
>>
>> I'm thinking of replacing the pickup coil, but wonder if there's a test
>> for this. It's a 3 wire model.
>>
>> BTW, I get no computer codes off the thing.
>>
>> Thanks for any help.
>
> http://revbeergoggles.com/cps/
>
> 1-2 second run indicates a sensor/relay fault is shutting down the
> engine or the computer isn't getting an indication the engine
> has actually started. This can be from a failed camshaft position
> sensor or crankshaft position sensor. In some cases it can also
> be a failing ASD relay or a blown fuse. Some times a faulty ignition
> coil can do this as well.
I have no idea what activates/deactivates the ASD relay. I've heard read
of oil pressure ones and ones under the drivers seat, but haven't found
one.
I know a FSM would be nice.
> Chuck did pass the time by typing:
>> My kid's Jeep now starts and run for 1-2 seconds, then stalls. I checked
>> the ohms on the CPS and it's infinite as be between 2-3 pins. I also
>> check the TPS voltage and fuel pressure and both were fine. The fuel
>> pressure doesn't drop when the engine cuts out. I'm not sure if the
>> injectors are shuting down cutting off fuel or the spark is quitting, or
>> both.
>>
>> I'm thinking of replacing the pickup coil, but wonder if there's a test
>> for this. It's a 3 wire model.
>>
>> BTW, I get no computer codes off the thing.
>>
>> Thanks for any help.
>
> http://revbeergoggles.com/cps/
>
> 1-2 second run indicates a sensor/relay fault is shutting down the
> engine or the computer isn't getting an indication the engine
> has actually started. This can be from a failed camshaft position
> sensor or crankshaft position sensor. In some cases it can also
> be a failing ASD relay or a blown fuse. Some times a faulty ignition
> coil can do this as well.
I have no idea what activates/deactivates the ASD relay. I've heard read
of oil pressure ones and ones under the drivers seat, but haven't found
one.
I know a FSM would be nice.
08-28-2005, 08:28 AM
#13
Guest
Posts: n/a
Re: 93 Grand Cherokee Ignition Question
On 2005-08-27, DougW <post.replies@invalid.address> wrote:
> Chuck did pass the time by typing:
>> My kid's Jeep now starts and run for 1-2 seconds, then stalls. I checked
>> the ohms on the CPS and it's infinite as be between 2-3 pins. I also
>> check the TPS voltage and fuel pressure and both were fine. The fuel
>> pressure doesn't drop when the engine cuts out. I'm not sure if the
>> injectors are shuting down cutting off fuel or the spark is quitting, or
>> both.
>>
>> I'm thinking of replacing the pickup coil, but wonder if there's a test
>> for this. It's a 3 wire model.
>>
>> BTW, I get no computer codes off the thing.
>>
>> Thanks for any help.
>
> http://revbeergoggles.com/cps/
>
> 1-2 second run indicates a sensor/relay fault is shutting down the
> engine or the computer isn't getting an indication the engine
> has actually started. This can be from a failed camshaft position
> sensor or crankshaft position sensor. In some cases it can also
> be a failing ASD relay or a blown fuse. Some times a faulty ignition
> coil can do this as well.
I have no idea what activates/deactivates the ASD relay. I've heard read
of oil pressure ones and ones under the drivers seat, but haven't found
one.
I know a FSM would be nice.
> Chuck did pass the time by typing:
>> My kid's Jeep now starts and run for 1-2 seconds, then stalls. I checked
>> the ohms on the CPS and it's infinite as be between 2-3 pins. I also
>> check the TPS voltage and fuel pressure and both were fine. The fuel
>> pressure doesn't drop when the engine cuts out. I'm not sure if the
>> injectors are shuting down cutting off fuel or the spark is quitting, or
>> both.
>>
>> I'm thinking of replacing the pickup coil, but wonder if there's a test
>> for this. It's a 3 wire model.
>>
>> BTW, I get no computer codes off the thing.
>>
>> Thanks for any help.
>
> http://revbeergoggles.com/cps/
>
> 1-2 second run indicates a sensor/relay fault is shutting down the
> engine or the computer isn't getting an indication the engine
> has actually started. This can be from a failed camshaft position
> sensor or crankshaft position sensor. In some cases it can also
> be a failing ASD relay or a blown fuse. Some times a faulty ignition
> coil can do this as well.
I have no idea what activates/deactivates the ASD relay. I've heard read
of oil pressure ones and ones under the drivers seat, but haven't found
one.
I know a FSM would be nice.
08-28-2005, 08:28 AM
#14
Guest
Posts: n/a
Re: 93 Grand Cherokee Ignition Question
On 2005-08-27, DougW <post.replies@invalid.address> wrote:
> Chuck did pass the time by typing:
>> My kid's Jeep now starts and run for 1-2 seconds, then stalls. I checked
>> the ohms on the CPS and it's infinite as be between 2-3 pins. I also
>> check the TPS voltage and fuel pressure and both were fine. The fuel
>> pressure doesn't drop when the engine cuts out. I'm not sure if the
>> injectors are shuting down cutting off fuel or the spark is quitting, or
>> both.
>>
>> I'm thinking of replacing the pickup coil, but wonder if there's a test
>> for this. It's a 3 wire model.
>>
>> BTW, I get no computer codes off the thing.
>>
>> Thanks for any help.
>
> http://revbeergoggles.com/cps/
>
> 1-2 second run indicates a sensor/relay fault is shutting down the
> engine or the computer isn't getting an indication the engine
> has actually started. This can be from a failed camshaft position
> sensor or crankshaft position sensor. In some cases it can also
> be a failing ASD relay or a blown fuse. Some times a faulty ignition
> coil can do this as well.
I have no idea what activates/deactivates the ASD relay. I've heard read
of oil pressure ones and ones under the drivers seat, but haven't found
one.
I know a FSM would be nice.
> Chuck did pass the time by typing:
>> My kid's Jeep now starts and run for 1-2 seconds, then stalls. I checked
>> the ohms on the CPS and it's infinite as be between 2-3 pins. I also
>> check the TPS voltage and fuel pressure and both were fine. The fuel
>> pressure doesn't drop when the engine cuts out. I'm not sure if the
>> injectors are shuting down cutting off fuel or the spark is quitting, or
>> both.
>>
>> I'm thinking of replacing the pickup coil, but wonder if there's a test
>> for this. It's a 3 wire model.
>>
>> BTW, I get no computer codes off the thing.
>>
>> Thanks for any help.
>
> http://revbeergoggles.com/cps/
>
> 1-2 second run indicates a sensor/relay fault is shutting down the
> engine or the computer isn't getting an indication the engine
> has actually started. This can be from a failed camshaft position
> sensor or crankshaft position sensor. In some cases it can also
> be a failing ASD relay or a blown fuse. Some times a faulty ignition
> coil can do this as well.
I have no idea what activates/deactivates the ASD relay. I've heard read
of oil pressure ones and ones under the drivers seat, but haven't found
one.
I know a FSM would be nice.
08-28-2005, 08:28 AM
#15
Guest
Posts: n/a
Re: 93 Grand Cherokee Ignition Question
On 2005-08-27, DougW <post.replies@invalid.address> wrote:
> Chuck did pass the time by typing:
>> My kid's Jeep now starts and run for 1-2 seconds, then stalls. I checked
>> the ohms on the CPS and it's infinite as be between 2-3 pins. I also
>> check the TPS voltage and fuel pressure and both were fine. The fuel
>> pressure doesn't drop when the engine cuts out. I'm not sure if the
>> injectors are shuting down cutting off fuel or the spark is quitting, or
>> both.
>>
>> I'm thinking of replacing the pickup coil, but wonder if there's a test
>> for this. It's a 3 wire model.
>>
>> BTW, I get no computer codes off the thing.
>>
>> Thanks for any help.
>
> http://revbeergoggles.com/cps/
>
> 1-2 second run indicates a sensor/relay fault is shutting down the
> engine or the computer isn't getting an indication the engine
> has actually started. This can be from a failed camshaft position
> sensor or crankshaft position sensor. In some cases it can also
> be a failing ASD relay or a blown fuse. Some times a faulty ignition
> coil can do this as well.
I have no idea what activates/deactivates the ASD relay. I've heard read
of oil pressure ones and ones under the drivers seat, but haven't found
one.
I know a FSM would be nice.
> Chuck did pass the time by typing:
>> My kid's Jeep now starts and run for 1-2 seconds, then stalls. I checked
>> the ohms on the CPS and it's infinite as be between 2-3 pins. I also
>> check the TPS voltage and fuel pressure and both were fine. The fuel
>> pressure doesn't drop when the engine cuts out. I'm not sure if the
>> injectors are shuting down cutting off fuel or the spark is quitting, or
>> both.
>>
>> I'm thinking of replacing the pickup coil, but wonder if there's a test
>> for this. It's a 3 wire model.
>>
>> BTW, I get no computer codes off the thing.
>>
>> Thanks for any help.
>
> http://revbeergoggles.com/cps/
>
> 1-2 second run indicates a sensor/relay fault is shutting down the
> engine or the computer isn't getting an indication the engine
> has actually started. This can be from a failed camshaft position
> sensor or crankshaft position sensor. In some cases it can also
> be a failing ASD relay or a blown fuse. Some times a faulty ignition
> coil can do this as well.
I have no idea what activates/deactivates the ASD relay. I've heard read
of oil pressure ones and ones under the drivers seat, but haven't found
one.
I know a FSM would be nice.
08-28-2005, 02:14 PM
#16
Guest
Posts: n/a
Re: 93 Grand Cherokee Ignition Question
Chuck did pass the time by typing:
> I have no idea what activates/deactivates the ASD relay. I've heard read
> of oil pressure ones and ones under the drivers seat, but haven't found
> one.
The ECU/Computer controls the ASD realy. ASD or Automatic ShutDown is
basically the engines panic button.
http://www.revbeergoggles.com/temp/
ZJ-13 - 18
--
DougW
> I have no idea what activates/deactivates the ASD relay. I've heard read
> of oil pressure ones and ones under the drivers seat, but haven't found
> one.
The ECU/Computer controls the ASD realy. ASD or Automatic ShutDown is
basically the engines panic button.
http://www.revbeergoggles.com/temp/
ZJ-13 - 18
--
DougW
08-28-2005, 02:14 PM
#17
Guest
Posts: n/a
Re: 93 Grand Cherokee Ignition Question
Chuck did pass the time by typing:
> I have no idea what activates/deactivates the ASD relay. I've heard read
> of oil pressure ones and ones under the drivers seat, but haven't found
> one.
The ECU/Computer controls the ASD realy. ASD or Automatic ShutDown is
basically the engines panic button.
http://www.revbeergoggles.com/temp/
ZJ-13 - 18
--
DougW
> I have no idea what activates/deactivates the ASD relay. I've heard read
> of oil pressure ones and ones under the drivers seat, but haven't found
> one.
The ECU/Computer controls the ASD realy. ASD or Automatic ShutDown is
basically the engines panic button.
http://www.revbeergoggles.com/temp/
ZJ-13 - 18
--
DougW
08-28-2005, 02:14 PM
#18
Guest
Posts: n/a
Re: 93 Grand Cherokee Ignition Question
Chuck did pass the time by typing:
> I have no idea what activates/deactivates the ASD relay. I've heard read
> of oil pressure ones and ones under the drivers seat, but haven't found
> one.
The ECU/Computer controls the ASD realy. ASD or Automatic ShutDown is
basically the engines panic button.
http://www.revbeergoggles.com/temp/
ZJ-13 - 18
--
DougW
> I have no idea what activates/deactivates the ASD relay. I've heard read
> of oil pressure ones and ones under the drivers seat, but haven't found
> one.
The ECU/Computer controls the ASD realy. ASD or Automatic ShutDown is
basically the engines panic button.
http://www.revbeergoggles.com/temp/
ZJ-13 - 18
--
DougW
08-28-2005, 02:14 PM
#19
Guest
Posts: n/a
Re: 93 Grand Cherokee Ignition Question
Chuck did pass the time by typing:
> I have no idea what activates/deactivates the ASD relay. I've heard read
> of oil pressure ones and ones under the drivers seat, but haven't found
> one.
The ECU/Computer controls the ASD realy. ASD or Automatic ShutDown is
basically the engines panic button.
http://www.revbeergoggles.com/temp/
ZJ-13 - 18
--
DougW
> I have no idea what activates/deactivates the ASD relay. I've heard read
> of oil pressure ones and ones under the drivers seat, but haven't found
> one.
The ECU/Computer controls the ASD realy. ASD or Automatic ShutDown is
basically the engines panic button.
http://www.revbeergoggles.com/temp/
ZJ-13 - 18
--
DougW
08-28-2005, 04:15 PM
#20
Guest
Posts: n/a
Re: 93 Grand Cherokee Ignition Question
On 2005-08-28, DougW <post.replies@invalid.address> wrote:
> Chuck did pass the time by typing:
>
>> I have no idea what activates/deactivates the ASD relay. I've heard read
>> of oil pressure ones and ones under the drivers seat, but haven't found
>> one.
>
> The ECU/Computer controls the ASD realy. ASD or Automatic ShutDown is
> basically the engines panic button.
> http://www.revbeergoggles.com/temp/
> ZJ-13 - 18
>
I guess I'm half blind. The third or fourth time of taking out the
fuses, I spotted the burn in the 40 panel fuse. I should have known that
the absence of any bells was wrong and I never tried windows, heater,
radio, etc. I was too focused on the fact that the dash gauges/lights
were working.
It seems the thing is running better than before. I just wonder when
the cause of the blown fuse will rear its ugly head again.
Thanks, for all the help. Great stuff on the web site Doug, thanks.
Chuck
> Chuck did pass the time by typing:
>
>> I have no idea what activates/deactivates the ASD relay. I've heard read
>> of oil pressure ones and ones under the drivers seat, but haven't found
>> one.
>
> The ECU/Computer controls the ASD realy. ASD or Automatic ShutDown is
> basically the engines panic button.
> http://www.revbeergoggles.com/temp/
> ZJ-13 - 18
>
I guess I'm half blind. The third or fourth time of taking out the
fuses, I spotted the burn in the 40 panel fuse. I should have known that
the absence of any bells was wrong and I never tried windows, heater,
radio, etc. I was too focused on the fact that the dash gauges/lights
were working.
It seems the thing is running better than before. I just wonder when
the cause of the blown fuse will rear its ugly head again.
Thanks, for all the help. Great stuff on the web site Doug, thanks.
Chuck