Motor wont start if Temp is below 40F°
#11
02-04-2011, 11:33 AM
Q: WHY?
A: The PCM contains components that are sensitive to ESD shock. ESD stands for Electrostatic Discharge. The hairdryer will impart a POSITIVE charge >20KV upon not only the case but, also at the connector pins and, if the charge is strong enough, it will flow from CASE to the inside components via ground legs of the ICs and diodes.
ON the insides of the ESD sensitive components, there are wirebonds as well as super fine traces made up of Au plating over Ni and Cu. When the hi-voltage reaches these components, the wirebonds (.0007-.001, Au wire) and/or the traces will POP like a fuse. There's also P/N junctions on some die as well as at the diode component level that will blow instantly.
Basically, things are going to pop like fuses thus, kills the PCM functionality to a degree. If it doesn't kill it, it may be sporadic failures or, latent failure during use.
The other problem is, when going from a COLD TEMP to HOT TEMP - what is witnessed?
A: Condensation is witnessed and, this means, moisture is present thus condensing on the outside of the case as well as on the inside of the PCM. The last thing you want to do here is to have a live PCM with condensation inside. This is a sure way to create potential for a SHORT.
Again, please do not use a hairdryer.
Regards,
CM
#12
02-04-2011, 12:32 PM
Join Date: Feb 2011
Location: MTY
Posts: 11
Likes: 0
Received 0 Likes
on
0 Posts
This is common on some models due to a failure at the PCM level. I've now helped three people with this same failure mode- won't start at below X-temp.
Here's what I want you to do and, it's really simple. You're going to run a poor man's THERMAL CYCLING TEST on the PCM.
PROCEDURE:
REMOVE the negative lead (-) from the battery and wait 1-3 minutes for all power to bleed off to ground.
REMOVE THE COVER ON THE PCM.
REMOVE the THREE connectors at the PCM.
REMOVE THE PCM
TAKE THE PCM INTO THE HOUSE and allow it to warm to AMBIENT TEMP.
RE-INSTALL PCM INTO TRUCK
CONNECT THREE CONNECTORS
NOTE: MAKE SURE ALL power is off on the vehicle. NO lights are on, no radio is on, all doors are closed (DOME LAMP) is OFF etc etc PRIOR to connecting the NEG (-) BAT terminal.
RECONNECT NEG (-) BAT TERMINAL.
START TRUCK.
<IF> the truck turns over and it starts when PCM is at AMBIENT TEMP- you've got a failure at the PCM level and, most likely, it's going to be the ground control circuit and or COM. If this is the case, leave the PCM in the truck overnight and try to start it in the morning.
<IF> it does not start in the morning t AT COLD: repeat the above test for a total of five times to gain statistics in confidence level that a failure at the PCM level is indeed the root cause for failure and not a BAD CONNECTION. If it starts at AMBIENT TEMP all times, it's rooted at the PCM level.
<IF> the truck does not start under any of those tests, it's either going to be rooted in either the ignition or fuel delivery system level.
CM
Here's what I want you to do and, it's really simple. You're going to run a poor man's THERMAL CYCLING TEST on the PCM.
PROCEDURE:
REMOVE the negative lead (-) from the battery and wait 1-3 minutes for all power to bleed off to ground.
REMOVE THE COVER ON THE PCM.
REMOVE the THREE connectors at the PCM.
REMOVE THE PCM
TAKE THE PCM INTO THE HOUSE and allow it to warm to AMBIENT TEMP.
RE-INSTALL PCM INTO TRUCK
CONNECT THREE CONNECTORS
NOTE: MAKE SURE ALL power is off on the vehicle. NO lights are on, no radio is on, all doors are closed (DOME LAMP) is OFF etc etc PRIOR to connecting the NEG (-) BAT terminal.
RECONNECT NEG (-) BAT TERMINAL.
START TRUCK.
<IF> the truck turns over and it starts when PCM is at AMBIENT TEMP- you've got a failure at the PCM level and, most likely, it's going to be the ground control circuit and or COM. If this is the case, leave the PCM in the truck overnight and try to start it in the morning.
<IF> it does not start in the morning t AT COLD: repeat the above test for a total of five times to gain statistics in confidence level that a failure at the PCM level is indeed the root cause for failure and not a BAD CONNECTION. If it starts at AMBIENT TEMP all times, it's rooted at the PCM level.
<IF> the truck does not start under any of those tests, it's either going to be rooted in either the ignition or fuel delivery system level.
CM
didnt start .as always it crancks but motor wont run at all no even a sign .
#13
02-04-2011, 12:38 PM
Ok, that rules that out.
Let me ask you this:
When you turn KEY <ON>, do you hear any clicking coming from the PDC box under the hood?
When KEY <ON> is initiated, the PCM enables the GROUND PATH for BOTH ASD and FUEL PUMP RELAY. Both relays will produce and audible click when the GROUND is switched in circuit. Listen for that and get back to me.
Do you own a multi-meter by chance?
There's quite a few things for what is called, a NO START CONDITION.
1. Crank Position Sensor is shorted, or, failed 5V pulse at input of PCM
2. Cam Position Sensor is shorted, or, failed to generate reference at input of PCM
3. B+ is not present - loss of source or, source is below the minimum acceptable limits for PCM operation thus, the PCM will not power to an <ON> state.
Those are the starting points. I would start with the simplest things first.
-Verify B+ at source (BAT) should be >12 volts.
-Verify SPARK.
HOW: Using a spare spark plug of known good working condition, attach it to a spare ignition wire of known good state.
REMOVE: coil wire off the coil and set aside.
ATTACH ignition wire with spark plug.
POSITION spark plug to CHASSIS GROUND.
START truck and look for spark across gap of plug. NOTE: You will need an assistant for this method. If it's just yourself, you can use a clamp to tie the plug to ground and place it in the window where you can see it.
Start with those two items first and report back.
CM
Let me ask you this:
When you turn KEY <ON>, do you hear any clicking coming from the PDC box under the hood?
When KEY <ON> is initiated, the PCM enables the GROUND PATH for BOTH ASD and FUEL PUMP RELAY. Both relays will produce and audible click when the GROUND is switched in circuit. Listen for that and get back to me.
Do you own a multi-meter by chance?
There's quite a few things for what is called, a NO START CONDITION.
1. Crank Position Sensor is shorted, or, failed 5V pulse at input of PCM
2. Cam Position Sensor is shorted, or, failed to generate reference at input of PCM
3. B+ is not present - loss of source or, source is below the minimum acceptable limits for PCM operation thus, the PCM will not power to an <ON> state.
Those are the starting points. I would start with the simplest things first.
-Verify B+ at source (BAT) should be >12 volts.
-Verify SPARK.
HOW: Using a spare spark plug of known good working condition, attach it to a spare ignition wire of known good state.
REMOVE: coil wire off the coil and set aside.
ATTACH ignition wire with spark plug.
POSITION spark plug to CHASSIS GROUND.
START truck and look for spark across gap of plug. NOTE: You will need an assistant for this method. If it's just yourself, you can use a clamp to tie the plug to ground and place it in the window where you can see it.
Start with those two items first and report back.
CM
Last edited by cmckenna; 02-04-2011 at 12:50 PM.
#14
02-04-2011, 12:44 PM
Join Date: Feb 2011
Location: MTY
Posts: 11
Likes: 0
Received 0 Likes
on
0 Posts
^^ i wonder how well it would work to use a hair dryer to blow hot air on the pcm for about 5-10 minutes to accelerate the warm up period without removing it from the truck. just get it warm, not hot.
to the OP, did this problem start with the Accel coil? if so, blow warm air on it too... then replace the damn thing.
since the stating fluid didn't help, i'd focus on electrical too.
to the OP, did this problem start with the Accel coil? if so, blow warm air on it too... then replace the damn thing.
since the stating fluid didn't help, i'd focus on electrical too.
i got the accel coil thinking that woul solve the problem and it didnt i got an other problem with that coil (the truck working perfect it turned off ,some one told me it was becouse that coil supplied more energy than the original coil which i dont kow what detected that + energy and turned off the truck i would have to wait 10+ min. so it could start again.
think she wants a heated room lolo
#15
02-04-2011, 12:52 PM
Join Date: Feb 2011
Location: MTY
Posts: 11
Likes: 0
Received 0 Likes
on
0 Posts
#16
02-04-2011, 02:13 PM
#17
02-04-2011, 03:56 PM
Join Date: Feb 2011
Location: MTY
Posts: 11
Likes: 0
Received 0 Likes
on
0 Posts
#18
02-04-2011, 03:56 PM
#19
02-04-2011, 04:09 PM
Join Date: Feb 2011
Location: MTY
Posts: 11
Likes: 0
Received 0 Likes
on
0 Posts
Temp. at 11 am 43°F motor started just as if it was a brand new truck.
#20
02-04-2011, 04:19 PM
Join Date: Feb 2011
Location: MTY
Posts: 11
Likes: 0
Received 0 Likes
on
0 Posts
