My neighbor (and friend) has a 95' Grand Cherokee Laredo that has an
odd starting problem...

He has to leave the radio on and wait for it to warm up (completely
power on) before he can crank the engine. If he attempts to start it
before the radio is fully on, the jeep fails to start and the alarm
goes off.

He has replaced a few things in the last year, mostly cosmetic, but he
did replace the computer because he suspected it might been part of
the problem with the tranny. Since then he resolved the tranny
problem, but still has this odd power/start problem.

Other than working with the tranny, the onlyother things replaced have
been the computer, radio antenna, door guard panel and rear bumper
(loose). Anyone got any guesses?

 

You are describing a vehicle that has lost it's body ground so it needs
to steal the ground through another route. It has picked the radio as
the ground path for now, but that won't last. The radio will fry.

I am not 100% for sure on the GC where the grounds are, but I believe
one is from the battery to the fender and maybe one is a mesh strap
across one engine mount. The Cherokee has a mesh strap from the rear of
the engine head to the firewall.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's
Canadian Off Road Trips Photos: Non members can still view!
Jan/06 http://www.imagestation.com/album/pi...?id=2115147590
(More Off Road album links at bottom of the view page)

Chameleon@nospam.com wrote:
>
> My neighbor (and friend) has a 95' Grand Cherokee Laredo that has an
> odd starting problem...
>
> He has to leave the radio on and wait for it to warm up (completely
> power on) before he can crank the engine. If he attempts to start it
> before the radio is fully on, the jeep fails to start and the alarm
> goes off.
>
> He has replaced a few things in the last year, mostly cosmetic, but he
> did replace the computer because he suspected it might been part of
> the problem with the tranny. Since then he resolved the tranny
> problem, but still has this odd power/start problem.
>
> Other than working with the tranny, the onlyother things replaced have
> been the computer, radio antenna, door guard panel and rear bumper
> (loose). Anyone got any guesses?

 

You are describing a vehicle that has lost it's body ground so it needs
to steal the ground through another route. It has picked the radio as
the ground path for now, but that won't last. The radio will fry.

I am not 100% for sure on the GC where the grounds are, but I believe
one is from the battery to the fender and maybe one is a mesh strap
across one engine mount. The Cherokee has a mesh strap from the rear of
the engine head to the firewall.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's
Canadian Off Road Trips Photos: Non members can still view!
Jan/06 http://www.imagestation.com/album/pi...?id=2115147590
(More Off Road album links at bottom of the view page)

Chameleon@nospam.com wrote:
>
> My neighbor (and friend) has a 95' Grand Cherokee Laredo that has an
> odd starting problem...
>
> He has to leave the radio on and wait for it to warm up (completely
> power on) before he can crank the engine. If he attempts to start it
> before the radio is fully on, the jeep fails to start and the alarm
> goes off.
>
> He has replaced a few things in the last year, mostly cosmetic, but he
> did replace the computer because he suspected it might been part of
> the problem with the tranny. Since then he resolved the tranny
> problem, but still has this odd power/start problem.
>
> Other than working with the tranny, the onlyother things replaced have
> been the computer, radio antenna, door guard panel and rear bumper
> (loose). Anyone got any guesses?

 

You are describing a vehicle that has lost it's body ground so it needs
to steal the ground through another route. It has picked the radio as
the ground path for now, but that won't last. The radio will fry.

I am not 100% for sure on the GC where the grounds are, but I believe
one is from the battery to the fender and maybe one is a mesh strap
across one engine mount. The Cherokee has a mesh strap from the rear of
the engine head to the firewall.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's
Canadian Off Road Trips Photos: Non members can still view!
Jan/06 http://www.imagestation.com/album/pi...?id=2115147590
(More Off Road album links at bottom of the view page)

Chameleon@nospam.com wrote:
>
> My neighbor (and friend) has a 95' Grand Cherokee Laredo that has an
> odd starting problem...
>
> He has to leave the radio on and wait for it to warm up (completely
> power on) before he can crank the engine. If he attempts to start it
> before the radio is fully on, the jeep fails to start and the alarm
> goes off.
>
> He has replaced a few things in the last year, mostly cosmetic, but he
> did replace the computer because he suspected it might been part of
> the problem with the tranny. Since then he resolved the tranny
> problem, but still has this odd power/start problem.
>
> Other than working with the tranny, the onlyother things replaced have
> been the computer, radio antenna, door guard panel and rear bumper
> (loose). Anyone got any guesses?

 

You are describing a vehicle that has lost it's body ground so it needs
to steal the ground through another route. It has picked the radio as
the ground path for now, but that won't last. The radio will fry.

I am not 100% for sure on the GC where the grounds are, but I believe
one is from the battery to the fender and maybe one is a mesh strap
across one engine mount. The Cherokee has a mesh strap from the rear of
the engine head to the firewall.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's
Canadian Off Road Trips Photos: Non members can still view!
Jan/06 http://www.imagestation.com/album/pi...?id=2115147590
(More Off Road album links at bottom of the view page)

Chameleon@nospam.com wrote:
>
> My neighbor (and friend) has a 95' Grand Cherokee Laredo that has an
> odd starting problem...
>
> He has to leave the radio on and wait for it to warm up (completely
> power on) before he can crank the engine. If he attempts to start it
> before the radio is fully on, the jeep fails to start and the alarm
> goes off.
>
> He has replaced a few things in the last year, mostly cosmetic, but he
> did replace the computer because he suspected it might been part of
> the problem with the tranny. Since then he resolved the tranny
> problem, but still has this odd power/start problem.
>
> Other than working with the tranny, the onlyother things replaced have
> been the computer, radio antenna, door guard panel and rear bumper
> (loose). Anyone got any guesses?

 

Chameleon@nospam.com proclaimed:

> My neighbor (and friend) has a 95' Grand Cherokee Laredo that has an
> odd starting problem...
>
> He has to leave the radio on and wait for it to warm up (completely
> power on) before he can crank the engine. If he attempts to start it
> before the radio is fully on, the jeep fails to start and the alarm
> goes off.
>
> He has replaced a few things in the last year, mostly cosmetic, but he
> did replace the computer because he suspected it might been part of
> the problem with the tranny. Since then he resolved the tranny
> problem, but still has this odd power/start problem.
>
> Other than working with the tranny, the onlyother things replaced have
> been the computer, radio antenna, door guard panel and rear bumper
> (loose). Anyone got any guesses?

The one guess would be an aftermarket radio, poorly installed.

It is a fairly simple circuit IF nobody has messed with it.

Plus 12 is fed off Fuse 12 in the PDC to the ignition switch and from
there is fed [thru the clutch pedal sensor if manual] directly to the
energizing side of the starter relay.

The ground side of the starter relay is fed thru the park/neutral switch
on an auto transmission [or directly to ground on a manual].

You can measure for that +12 at the starter relay as someone turns the
key to the start position. A braindead aftermarket installer or a bad
ignition switch are about all that can prevent it from showing up,
presuming anything else at all on the ignition switch works.

The ground is a bit trickier, but you can check for it again at the
starter relay socket by having a friend put the tranny in and out of
park if an auto...otherwise the ground should always be there.

The above just pulls the starter relay.

The actual power to the starter solenoid comes from Fuse 11 in the PDC
and goes straight thru the starter relay normal open contacts to the
starter solenoid. A bit Sears screwdriver can jump across that
solenoid if suspect. You should be able to start the car by just
jumping across the starter relay socket [with ignition on] from pin 30
[comes off the battery thru fuse 11] to pin 87 that feeds the starter
solenoid.

Check very carefully near the alternator and battery to make sure that
you have a very good and heavy wire straight from the battery to a nice
tight ground at the fenderwall.

 

Chameleon@nospam.com proclaimed:

> My neighbor (and friend) has a 95' Grand Cherokee Laredo that has an
> odd starting problem...
>
> He has to leave the radio on and wait for it to warm up (completely
> power on) before he can crank the engine. If he attempts to start it
> before the radio is fully on, the jeep fails to start and the alarm
> goes off.
>
> He has replaced a few things in the last year, mostly cosmetic, but he
> did replace the computer because he suspected it might been part of
> the problem with the tranny. Since then he resolved the tranny
> problem, but still has this odd power/start problem.
>
> Other than working with the tranny, the onlyother things replaced have
> been the computer, radio antenna, door guard panel and rear bumper
> (loose). Anyone got any guesses?

The one guess would be an aftermarket radio, poorly installed.

It is a fairly simple circuit IF nobody has messed with it.

Plus 12 is fed off Fuse 12 in the PDC to the ignition switch and from
there is fed [thru the clutch pedal sensor if manual] directly to the
energizing side of the starter relay.

The ground side of the starter relay is fed thru the park/neutral switch
on an auto transmission [or directly to ground on a manual].

You can measure for that +12 at the starter relay as someone turns the
key to the start position. A braindead aftermarket installer or a bad
ignition switch are about all that can prevent it from showing up,
presuming anything else at all on the ignition switch works.

The ground is a bit trickier, but you can check for it again at the
starter relay socket by having a friend put the tranny in and out of
park if an auto...otherwise the ground should always be there.

The above just pulls the starter relay.

The actual power to the starter solenoid comes from Fuse 11 in the PDC
and goes straight thru the starter relay normal open contacts to the
starter solenoid. A bit Sears screwdriver can jump across that
solenoid if suspect. You should be able to start the car by just
jumping across the starter relay socket [with ignition on] from pin 30
[comes off the battery thru fuse 11] to pin 87 that feeds the starter
solenoid.

Check very carefully near the alternator and battery to make sure that
you have a very good and heavy wire straight from the battery to a nice
tight ground at the fenderwall.

 

Chameleon@nospam.com proclaimed:

> My neighbor (and friend) has a 95' Grand Cherokee Laredo that has an
> odd starting problem...
>
> He has to leave the radio on and wait for it to warm up (completely
> power on) before he can crank the engine. If he attempts to start it
> before the radio is fully on, the jeep fails to start and the alarm
> goes off.
>
> He has replaced a few things in the last year, mostly cosmetic, but he
> did replace the computer because he suspected it might been part of
> the problem with the tranny. Since then he resolved the tranny
> problem, but still has this odd power/start problem.
>
> Other than working with the tranny, the onlyother things replaced have
> been the computer, radio antenna, door guard panel and rear bumper
> (loose). Anyone got any guesses?

The one guess would be an aftermarket radio, poorly installed.

It is a fairly simple circuit IF nobody has messed with it.

Plus 12 is fed off Fuse 12 in the PDC to the ignition switch and from
there is fed [thru the clutch pedal sensor if manual] directly to the
energizing side of the starter relay.

The ground side of the starter relay is fed thru the park/neutral switch
on an auto transmission [or directly to ground on a manual].

You can measure for that +12 at the starter relay as someone turns the
key to the start position. A braindead aftermarket installer or a bad
ignition switch are about all that can prevent it from showing up,
presuming anything else at all on the ignition switch works.

The ground is a bit trickier, but you can check for it again at the
starter relay socket by having a friend put the tranny in and out of
park if an auto...otherwise the ground should always be there.

The above just pulls the starter relay.

The actual power to the starter solenoid comes from Fuse 11 in the PDC
and goes straight thru the starter relay normal open contacts to the
starter solenoid. A bit Sears screwdriver can jump across that
solenoid if suspect. You should be able to start the car by just
jumping across the starter relay socket [with ignition on] from pin 30
[comes off the battery thru fuse 11] to pin 87 that feeds the starter
solenoid.

Check very carefully near the alternator and battery to make sure that
you have a very good and heavy wire straight from the battery to a nice
tight ground at the fenderwall.

 

Chameleon@nospam.com proclaimed:

> My neighbor (and friend) has a 95' Grand Cherokee Laredo that has an
> odd starting problem...
>
> He has to leave the radio on and wait for it to warm up (completely
> power on) before he can crank the engine. If he attempts to start it
> before the radio is fully on, the jeep fails to start and the alarm
> goes off.
>
> He has replaced a few things in the last year, mostly cosmetic, but he
> did replace the computer because he suspected it might been part of
> the problem with the tranny. Since then he resolved the tranny
> problem, but still has this odd power/start problem.
>
> Other than working with the tranny, the onlyother things replaced have
> been the computer, radio antenna, door guard panel and rear bumper
> (loose). Anyone got any guesses?

The one guess would be an aftermarket radio, poorly installed.

It is a fairly simple circuit IF nobody has messed with it.

Plus 12 is fed off Fuse 12 in the PDC to the ignition switch and from
there is fed [thru the clutch pedal sensor if manual] directly to the
energizing side of the starter relay.

The ground side of the starter relay is fed thru the park/neutral switch
on an auto transmission [or directly to ground on a manual].

You can measure for that +12 at the starter relay as someone turns the
key to the start position. A braindead aftermarket installer or a bad
ignition switch are about all that can prevent it from showing up,
presuming anything else at all on the ignition switch works.

The ground is a bit trickier, but you can check for it again at the
starter relay socket by having a friend put the tranny in and out of
park if an auto...otherwise the ground should always be there.

The above just pulls the starter relay.

The actual power to the starter solenoid comes from Fuse 11 in the PDC
and goes straight thru the starter relay normal open contacts to the
starter solenoid. A bit Sears screwdriver can jump across that
solenoid if suspect. You should be able to start the car by just
jumping across the starter relay socket [with ignition on] from pin 30
[comes off the battery thru fuse 11] to pin 87 that feeds the starter
solenoid.

Check very carefully near the alternator and battery to make sure that
you have a very good and heavy wire straight from the battery to a nice
tight ground at the fenderwall.

 

>On Sun, 19 Feb 2006 <lon.stowell@comcast.net> proclaimed:
>The one guess would be an aftermarket radio, poorly installed.

Still has the stock radio system. Only addition was a FM modulated
CD changer which resides in the rear of theJeep, just in front of
the reight rear wheel well. It's been there for years, no problems.


>It is a fairly simple circuit IF nobody has messed with it.
>
>Plus 12 is fed off Fuse 12 in the PDC to the ignition switch and from
>there is fed [thru the clutch pedal sensor if manual] directly to the
>energizing side of the starter relay.
>
>The ground side of the starter relay is fed thru the park/neutral switch
>on an auto transmission [or directly to ground on a manual].
>
>You can measure for that +12 at the starter relay as someone turns the
>key to the start position. A braindead aftermarket installer or a bad
>ignition switch are about all that can prevent it from showing up,
>presuming anything else at all on the ignition switch works.
>
>The ground is a bit trickier, but you can check for it again at the
>starter relay socket by having a friend put the tranny in and out of
>park if an auto...otherwise the ground should always be there.
>
>The above just pulls the starter relay.
>
>The actual power to the starter solenoid comes from Fuse 11 in the PDC
>and goes straight thru the starter relay normal open contacts to the
>starter solenoid. A bit Sears screwdriver can jump across that
>solenoid if suspect. You should be able to start the car by just
>jumping across the starter relay socket [with ignition on] from pin 30
>[comes off the battery thru fuse 11] to pin 87 that feeds the starter
>solenoid.
>
>Check very carefully near the alternator and battery to make sure that
>you have a very good and heavy wire straight from the battery to a nice
>tight ground at the fenderwall.