GMC Yukon won't turn over - random indicator lights

Cassabaum

Newbie
Joined
May 5, 2014
Messages
12
Points
0
I have a 2003 Yukon XL 5.3L that has normal indicator lights with ignition switch in the ON position. When turned to the START position, nothing happens (no click - nothing). The shift position indicator does not show what position it is in (the P, R, D, etc are lit, but not underline showing position). When ignition switch is turned off and key removed, the E-brake light, seat belt, and security lights all stay lit. Rear wiper randomly changes position.

Trouble-shooting steps we have taken:
1) Battery voltage was low (10.5) and would not hold a charge - battery old and probably stressed during trouble-shooting
2) Replaced battery, cleaned and checked all cables and connections (ground lugs) to frame and engine. Check all fuses (both engine compartment and interior). Checked for frayed, loose, or broken wires
3) Symptoms did not change
4) Measured supply (battery and ignition voltages) and grounds checked at Body Control Module (BCM)
5) Replaced BCM
6) Symptoms did not change

Seems not starting could be related to shift indicator not working, i.e. the system can't verify that it is in Park or Neutral to allow it to start. But, how does the fact that the indicator lights (i.e. E-brake, seat belt) related to the fact the system doesn't know what gear it is in??

We are stumped .... any ideas for additional trouble-shooting steps would be greatly appreciated!!
 

The old man

Hero Member
Joined
Aug 3, 2007
Messages
829
Points
16
Do you know if the ignition switch has been replaced in the past? There is a TSB on this that describes the situation that you are in now. It concerns the possibility that if the ignition switch may have been replaced in the past and may have been misindexed and cause a no start condition and some lights staying on after the key is turned to the off position. It calls for taking the ignition switch our and checking on the proper procedure to index the switch. Just a thought. My $.02 worth.
 

Gus

wrench
Joined
Dec 8, 2006
Messages
2,421
Points
36
Ignition switch is a possibility......have you been able to read any possible codes in all modules?
 

Cassabaum

Newbie
Joined
May 5, 2014
Messages
12
Points
0
Gus said:
Ignition switch is a possibility......have you been able to read any possible codes in all modules?
Ok, I feel really dumb now!! :-[ There was no check engine light so I didn't check for codes .. but, I should have! When I put on my code reader, I get, "Can't connect to OBD interface" What does that mean? A bad PCM? Bad clock or data line?

Thanks so much for the "kick in the head" to go read the codes.

What should I look for next?

Thanks!!
 

nickb2

Wrench. Diagnostic Tech.
Joined
Nov 22, 2008
Messages
10,996
Points
63
Location
St-Hyacinthe, Quebec, Canada
if you have no pcm communcation, check fuse to pcm, if wiring is ok ecm 1 or 2 fuse, after that check junction box, will have irish green in connectors or bad connection from vibration of engine. :thx
 

nickb2

Wrench. Diagnostic Tech.
Joined
Nov 22, 2008
Messages
10,996
Points
63
Location
St-Hyacinthe, Quebec, Canada
had a big problem with shorted o2 heat on passenger side, when engine in power and heater active, would blow fuse 2. but only at specific times. Is it cold or hot where you live. $.02 gave egr code for weeks intermitant code. check for bad wiring on passanger side o2 heater, may help. :idea:
 

NickD

wrench
Joined
Aug 28, 2007
Messages
4,986
Points
48
My scanner won't work either unless the ignition is working and turned on. Gus and that young Old Man already suggested this. Other problems with ignition switch with dirty contacts, do not get a sharp voltage to reset the program counters in the computers. So the program starts at any random number. It has to start at the beginning for the proper sequence or will get a mess.

Also the programs that run these things are stored in what is called flashram, and very subject to corruption. Even as an old retired engineer, would be more than happy to trade the five or six computer systems in my car for a good old fashion set of points.
 

Cassabaum

Newbie
Joined
May 5, 2014
Messages
12
Points
0
nickb2 said:
if you have no pcm communcation, check fuse to pcm, if wiring is ok ecm 1 or 2 fuse, after that check junction box, will have irish green in connectors or bad connection from vibration of engine. :thx
I have checked all the fuses with a voltmeter - they all test good. I noticed some pack rat dropping around the engine compartment fuse box, so I removed the fuse box from it's mount and examined all the wires for any damage.

I'm not sure what junction box you are referring to, but I am checking all connectors to and from the pcm

I'm not sure what to think at this point, I'm still confused with the symptoms: Car won't turn over; no "underline" on dash indicating what gear the vehicle is in; E-brake light is always on; Code reader "can not connect to OBD interface"

Where should I focus? PCM? Should I verify continuity of certain signals to/from the PCM?

Sorry if I missed something you or someone else has already suggested to do.

Thanks!
 

Cassabaum

Newbie
Joined
May 5, 2014
Messages
12
Points
0
The old man said:
Do you know if the ignition switch has been replaced in the past? There is a TSB on this that describes the situation that you are in now. It concerns the possibility that if the ignition switch may have been replaced in the past and may have been misindexed and cause a no start condition and some lights staying on after the key is turned to the off position. It calls for taking the ignition switch our and checking on the proper procedure to index the switch. Just a thought. My $.02 worth.
Where can I find the TSB for this situation? Could a bad ignition switch cause the "no underline" indicator for gear position and intermittent rear wiper?

Thanks for your patience, this one has really got me confused!
 

kev2

wrench
Joined
Nov 14, 2006
Messages
4,919
Points
48
Age
119
for no communication issue - check cavity #16 ALDL for voltage..and confirm the ground #4 use the attachment I added to ID cavities.

Is there a remote starter or aftermarket alarm?
My Colleague mentioned a TSB - was your ignition switch changed?

Answer that and we can look at the ign switch - 2003 is after the known problem years BUT without dbl checking would not rule it out..
 

Attachments

The old man

Hero Member
Joined
Aug 3, 2007
Messages
829
Points
16
I thought I would go ahead and post the TSB that refers to your year of Yukon along with other years also. In my opinion if the switch was misindexed or bad, it could leave on dash light and may cause a wiper to intermit etc.

Also I seen where they may have a recall on your vehicle concerning no light in gear selection in the dash. Would call gmc dealer and asked if that is so.
----Under certain conditions, the shift lever position indicator located in the instrument cluster may not illuminate. If the indicator does not illuminate, the driver may not know which gear the vehicle is in. This could result in the vehicle moving in an unintended direction, increasing the risk of a crash. Dealers will reprogram the instrument panel cluster to correct this concern. This recall is expected to begin on February 14, 2005. The General Motors recall number is 05023.-----

Have you checked what kev2 posted.
 

Attachments

Cassabaum

Newbie
Joined
May 5, 2014
Messages
12
Points
0
kev2 said:
for no communication issue - check cavity #16 ALDL for voltage..and confirm the ground #4 use the attachment I added to ID cavities.

Is there a remote starter or aftermarket alarm?
My Colleague mentioned a TSB - was your ignition switch changed?

Answer that and we can look at the ign switch - 2003 is after the known problem years BUT without dbl checking would not rule it out..
I checked the voltage and ground on pins 4 and 16. Looks good.

I reviewed the TSB your colleague sent. I don't know if the ignition switch has been replaced. We have had the vehicle about a year and have not replaced it in that time frame. The TSB mentions removing and re-installing the ign switch per procedure xyz; how can I find that procedure. Is that what I should do next?

Thanks so much for your patience and walking me through these steps. I have a sense of hope back that we can get to the bottom of this confusing problem :)

I really like this forum where you guys read each other's posts and key off what each other is saying.

Thanks again!!
 

Cassabaum

Newbie
Joined
May 5, 2014
Messages
12
Points
0
The old man said:
I thought I would go ahead and post the TSB that refers to your year of Yukon along with other years also. In my opinion if the switch was misindexed or bad, it could leave on dash light and may cause a wiper to intermit etc.

Also I seen where they may have a recall on your vehicle concerning no light in gear selection in the dash. Would call gmc dealer and asked if that is so.
----Under certain conditions, the shift lever position indicator located in the instrument cluster may not illuminate. If the indicator does not illuminate, the driver may not know which gear the vehicle is in. This could result in the vehicle moving in an unintended direction, increasing the risk of a crash. Dealers will reprogram the instrument panel cluster to correct this concern. This recall is expected to begin on February 14, 2005. The General Motors recall number is 05023.-----

Have you checked what kev2 posted.
Yes, I read kev2's post and checked the voltage and ground. I also read the TSB. It does mention many of the symptoms I am seeing. As I mentioned in my response to kev2, the TSB mentions removing and re-indexing the ignition switch. How do I find that procedure? Is that what i should do next?

Thanks so much for your response and time!
 

The old man

Hero Member
Joined
Aug 3, 2007
Messages
829
Points
16
How long has this problem been going on? Did it just happen lately? Were you driving it daily? Did it start and run ok in the past week or so? Need to know when this issue started.

Before you start replacing or indexing a switch you need to use the schematic below and check for voltages and continuity at various points. Like check for voltage at the neutral safety switch at the transmission when the key is in the "ON' position, voltages at the starter relay, voltages at the starter coming from the battery etc. and etc.. Have you tried jumping across the starter to see if the starter will actually work?
 

Attachments

kev2

wrench
Joined
Nov 14, 2006
Messages
4,919
Points
48
Age
119
1st - does this vehicle have a remote starter? that changes the circuits.
2nd- lets work the computer issue next-
you have 12v at terminal #16 and #4 is ground.... then conform YOUR code reader-
>>> suggestion take to autozone, advance, orielys parts stores for a FREE scan - might be nothing there BUT it will confirm and eliminate issues.

3rd- you can use a dvom so we can pick circuits to test for power in different key positions BUT #1 needs ans.
 
Top