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Tech Support/Research
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Electrical Problem

Doc Borneo:

Just to get back to the basics: Have you and/or the dealer checked all of the grounds for tightness and good connections? The locations are listed on this forum. Have you checked for tightness at all of the battery power connections under the truck, at the red jumper box, at the alternator, fuse box and at the starter solenoid? These are easiest to check to eliminate those loose or corroded cable connection issues that cause other electrical problems.

You have likely seen on this forum that corrosion builds up on fuse contacts, especially on the larger fuses. That is another item you can check yourself and clean any that don't look good to eliminate that as a possible cause.

And what does the dealer say about readings when they attach their dealer diagnostic tool, e.g. Tech 2, to the truck? Are they reading any trouble codes or seeing communication errors, e.g., with the powertrain control module? More specifically, are there any transmission codes? Have they tried using the Tech 2 or their other equivalent GM diagnostic tools to communicate with other electrical modules like the Body Control Module to verify that they are working properly?

You said the dealer told you: "It seems that the car gets constantly the information, that it´s driving around." I'm unsure how to interpret that- it sounds like a powertrain control circuit is constantly receiving power and sending information even with the truck shut off, but I don't know how that would be reflected on a diagnostic tool (all normal operating parameters like engine RPMs, throttle position, temperature, etc. would be zero) or how to diagnose it except to start looking at drain on the battery, but admittedly that is a long shot.


Good luck and keep us posted.
 

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Thanks for your quick response!
Just to get back to the basics: Have you and/or the dealer checked all of the grounds for tightness and good connections? The locations are listed on this forum. Have you checked for tightness at all of the battery power connections under the truck, at the red jumper box, at the alternator, fuse box and at the starter solenoid? These are easiest to check to eliminate those loose or corroded cable connection issues that cause other electrical problems.
Yes, I checked the main grounds. Nonetheless I forwarded the ground diagram from the "How to" library to the dealer. Being "just" an engineer I may miss some specific knowledge or may have made faults while checking.
You have likely seen on this forum that corrosion builds up on fuse contacts, especially on the larger fuses. That is another item you can check yourself and clean any that don't look good to eliminate that as a possible cause.
I checked all fuses in both boxes visually and with a flowmeter. Nothing found here.
And what does the dealer say about readings when they attach their dealer diagnostic tool, e.g. Tech 2, to the truck? Are they reading any trouble codes or seeing communication errors, e.g., with the powertrain control module? More specifically, are there any transmission codes? Have they tried using the Tech 2 or their other equivalent GM diagnostic tools to communicate with other electrical modules like the Body Control Module to verify that they are working properly?
I don´t know about the codes they´ve got. From my understanding they only see that the car seems to move when ignition is on. What surprises me a bit because even when driving speedo is on zero, just rev meter is working. And OBD is stating no connection with gear box. I try to get the exact codes from the diagnostic tool.

I`ve also forwarded the wiring diagram from the serial data bus (in the "Unknown Driver" slide deck). Even having checked that myself ... but as said, I may have overseen something.
 

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Doc
I assume "gearbox" is transmission and based on earlier post - automatic
The 05 SSR has TWO serial data line pin 2 of data link connector is single wire low speed net work -- pins 6 and 14 are high speed CAN network -- the TCM (transmission control module) communicates to the ECM (engine control module) through the CAN lines, It communicates with other modules from the low speed network -- No communication from the TCM on high speed network should set a code U0101 ( just the one module down - not the entire network) and if no communication with low speed U1024.
Code U0101 check continuity of wires shown on Eds diagram between ECM and TCM. the check the TCM for power and ground.
The following is from membership access of identifix.com and "direct hit search - no communication with TCM speedo inop.
Possible faulty power or ground for TCM or faulty TCM
1.. At key on, engine off verify the Orange wire at pin 32, the Pink wire at pin 31, and the Yellow wire at pin 11 all have battery voltage.
2. Verify a good ground on the Black/White wire at pin 49.
3. If OK, replace the TCM.
IMPORTANT - that these readings are taken while backprobing connector - DO NOT take reading with connector unplugged.

ASK Your dealership is they have a membership to identifix.com or iATN.com - they can access factory service manuals from these sites (not cheap) - You might consider purchase of factory service manual or see if a fanatic has an e-copy you could have.
Also the new TCM has to be programed you can not just put one in and go - they must have the proper equipment and access to GM's service programming -- SO NO Guessing!!!
Hopefully they find out no power or bad ground to TCM
 

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One more thing for assistance, from service manual

"Action Taken When the DTC Sets

The module uses a default value for the missing parameter. "

The diagnostic tool is showing the default values used so that the car can be driven in "limp Mode" . Hopefully they have tech 2 or newer, especially if they have to perform reprogramming. Tech 2 can "ping" a module and see if it will respond.

I AM NOT saying you have a bad TCM, I am saying it is possible and this information is provided to assist in testing it.

SOME ONE else -- didn't the welcome to SSR fanatic "kit" have a thumb drive with a service manual on it. I have one -- somewhere?? -- maybe someone that bought a spare could send it Doc in germany
 

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Why tach works, speedo doesn't

I was preparing some material for my advanced electrical class and wanted to discuss this case study. I did some more research to explain multiplexing and what was going on in terms that could be easily understood. I thought I might share this with some of the inquiring minds on this site.

Multiplexing is a way for various computers to share data over one or two lines of communication. These lines are called many things and operate at various speeds. Some terms are data bus and serial data lines. The speeds in this care are class 2 and GM high speed CAN (GM calls it High Speed GMLAN because of a slight difference). Multiplexing greatly reduces the size of the wiring harness.

In this case:
the engine speed is sent to the engine control module (ECM), the ECM then shares that info on the data bus
the vehicle speed signal is sent to the transmission control module (TCM) the TCM then shares that info on the data bus.
the instrument panel (IPC) looks to the class2 data line for engine speed data created from the ecm for the tachometer. The speedometer uses vehicle speed data from the TCM. The TCM is not communicating so no speedometer operation. (I would bet the gear selector display is not functioning either!)
the scan tool is displaying the default value for vehicle speed that it is using to allow the car to be driven somewhat. The same thing occurs on scan tool data display when you unplug coolant sensor - because it recognizes the voltage is not normal the scanner displays a calculated temperature the ECM is using but the voltage displayed is actual. This would explain the scan tool showing vehicle speed changing with car standing still. the computer is looking at engine speed and throttle position to guess what speed might be and is does not know if car is in park, reverse or drive.

The big question is why is the TCM not responding.

DOC make sure they also check connections - see GM tsb 09-06-03-004
 

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Back from my easter trip, I got a call from the dealer. Finally they gave up and couldn´t find the root cause. Being just licensed for US cars for EU market and not for US cars for US markets, they are not getting the needed support by Chevy itself ... well, at least that´s what they are telling me.

Thanks to xoxoxoBruce, I´ll get the Service Manual. Then I´ll go back to square zero and try again. Plus checking the stuff autoprof has posted of course.

Thank you so much much for your ongoing support!
 

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BlueStreak
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Where to start??
I have started personalizing my "New" Blue SSR. Have few minor issues to fix. One I had not noticed before is that the radio does not turn off when I open the Driver door but it does when I open the Passenger door. The window does it's index thing though so I am thinking is might be something other than the switch related to the door handle in the door. Any one have any good ideas where to start, before I rip into the door?

I would start a new thread for this but am unable to post anything except a Quick Reply!!
 

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Where to start??
I have started personalizing my "New" Blue SSR. Have few minor issues to fix. One I had not noticed before is that the radio does not turn off when I open the Driver door but it does when I open the Passenger door. The window does it's index thing though so I am thinking is might be something other than the switch related to the door handle in the door. Any one have any good ideas where to start, before I rip into the door?

I would start a new thread for this but am unable to post anything except a Quick Reply!!
Does the drivers window go back up when door is closed?
If the answer is no, then I would suggest the door LATCH switch or open wire.
The RDM (roof door module) opens window slightly using the door HANDLE switches as inputs - the RDM the closes the window after the RDM sees a door closed signal from the door LATCH switch.
The BCM uses the door LATCH switch to shut off the retained accessory power. (shut off radio when door is opened).
Both switches are built into the door latch -- Gry/BLK (pin B) goes to the latch switch -- grounded ( BLK wire pin D) when door is open
If window does close
The GRY/BLK wire is open between a splice and the BCM ( I can't post the diagram:banghead ) Lets hope not a bad BCM
NOTE there are three plugs on latch -- a three wire for latch and handle, a two wire for key switch input and another 2 wire for lock actuator
 

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BlueStreak
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The window goes up and down as it should with the status of the door but the radio remains on with the door open until timeout unless the passenger door is opened, then it goes off. Thanks for the information. I did not want to tear into the door until I knew what to look for. Is the GRY/BLK also accessible in the kick panel, so I could maybe check there before ripping into the door? or should I just wait until I go in to do Muth Mirrors?
 

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Does the DIC indicate the door is ajar?

Scan tool data will show a door ajar switch - I called it door latch switch:banghead

Driver Door Ajar Switch: The scan tool displays the state of the driver door. Active is open and inactive is closed.

Driver Door Handle: The scan toll displays the current state of the door handle switch. When the driver door handle is lifted the scan tool will display active and at rest will display inactive.

Driver Door Latch Lock Switch: The scan tool will display Yes if the driver door is locked and No if it is unlocked.

How to check wiring
Unplug three wire connector from latch.
With key on use a voltmeter and measure the voltages as follows

Place black meter lead in cavity for black wire
Place red lead in cavity with Gry/blk wire (door ajar signal wire) and record voltage
Move red voltmeter lead to LGrn/blk wire (door handle switch signal wire) record voltage
Both measurements should be similar and I believe these are 5 volt reference circuits. (slight possibility they are both higher)
If they are similar - problem in latch
If Gry/blk wire 0 (or real low) that wire is open and must be traced down

I do not know why - but GM shows the two different switches on two different diagrams: one is door ajar switches and the other is door ajar and indicators :puzzled:
 

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BlueStreak
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Thanks Autoprof. Where are you finding these drawings? Are they on the memory stick from Dinerman? I have not navigated that yet but am willing to try so I can see what I am up to. Past experience trying to navigate drawings has not been good because I do not know where to find the starting point. I am used to looking in a book so I can flip from page to page for ref.
 

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The window goes up and down as it should with the status of the door but the radio remains on with the door open until timeout unless the passenger door is opened, then it goes off. Thanks for the information. I did not want to tear into the door until I knew what to look for. Is the GRY/BLK also accessible in the kick panel, so I could maybe check there before ripping into the door? or should I just wait until I go in to do Muth Mirrors?
Sorry I was typing other reply when you posted this one
Yes the wire is in kick panel - connector C500 -terminal A1 gry/blk, A3 Lgn/Blk and A5 is the blk ground wire. You could check resistance between blk wire and gry blk wire (door harness side and connector unplugged) low resistance door open -- high resistance to infinite door closed

Better yet get a scan tool to check BCM and RDM data -- compare to each other and previous post info.

IF window goes back up the properly RDM is seeing the door close and I do not think problem in latch
 

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Hurray - yesterday the thumb drive with the Service Manuals arrived! Thank you so much, xoxoxoBruce!!! That´s really awesome stuff. I love this community - so many people caring to collect information and provide it to others. I´m still overwhelmed ...

My :yellow: is now in another workshop. A car electric spezialist is now supporting me in looking for the fault. The wiring diagrams are a great help to understand the "miracles" happening in the guts of my black boxes. So I keep fingers crossed to get her back to the street soon.
 

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Daily Driver
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Dinerman did a great service to the community putting together the Ultimate Key. It's a must have for anyone who doesn't want to throw money at their truck hoping fairies will come in the night and make everything better. Even if you can't do the work and finding someone familiar with the SSR is a joke, you can find someone who will do it if you have the reference materials.
 

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Thanks Autoprof. Where are you finding these drawings? Are they on the memory stick from Dinerman? I have not navigated that yet but am willing to try so I can see what I am up to. Past experience trying to navigate drawings has not been good because I do not know where to find the starting point. I am used to looking in a book so I can flip from page to page for ref.[/quote]

Sorry blue streak -- I did not see this post ---
I have not opened the drive from dinerman -- They are in my glove box, I think?
I have a subscription to identifix that i get though school (I teach auto at a community college) This service has access to many factory service manuals.
You would look in wiring diagrams of service manual
I did find a diagram which shows both the door ajar and handle switch on one page -- it was in the section of wiring diagram for theft deterrent.
You never replied -- DOES door ajar message come on DIC?
 

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My Permagrin is back!

Finally she´s back on the road. The TCM had to be changed, now the roof is working again, gear control, power, etc. is back. There was no root cause visible, but the guy is assuming, that it may came from a temporary short circuit fault between the battery cells. True or not? I don´t want to proof it and changed the battery too.

The only problem not being solved right now is traction control & ABS. Both are still showing the warning signs and are not working. Seems to be a dead sensor somewhere? But this I hope to find out later.

Important is, that I can drive & smile ... :grin2:

Keep you postet about the rest when I find the faults.
 

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The shop has the according software to get into the depth of the guts. So they could read it.

BTW, I got the guy wrong, the dead sensors are found too. But I don´t want to buy them in Germany. The TCM already cost about 600$ without programming just for the Hardware. And the sensors should cost about 120$ each (plus tax & work). I will try to get them in the States and pick it up when I (or a collegue) is having the next working trip in US.
 
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