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Amedee
Amedee, Cadillac Technician
Category: Cadillac
Satisfied Customers: 24429
Experience:  ASE certified Technician advanced level specialist. Wisconsin certified emissions state inspector
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My 2008 cadillac sts has No dash lights, no ignition switch

Customer Question

my 2008 cadillac sts has No dash lights, no ignition switch power, key fob remotes will not work. when i open my drivers door, instrument cluster does not turn on no interior lights. car will not start or do anything. Tech 2 does not communicate with much since i cant even turn ignition on since i have keyless start. can a bad engine ecm shut down the entire system?
JA: Soon. I'm trying to find the right Cadillac Mechanic for you right now. As soon as they are ready, I will let you know. The mechanics have tons of experience in that area. Do you happen to have the code?
Customer: unable to access any codes
JA: I'll pass this info along to the Cadillac Mechanic so that he can get you a quick fix. Anything else I can tell the Cadillac Mechanic before I connect you two?
Customer: nope
JA: Got it. Let's get this figured out. I'm sending you to a secure page on JustAnswer so you can place the $5 fully refundable deposit now. While you're filling out that form, I'll tell the Cadillac Mechanic about your situation and connect you two. You'll be on the road in no time.
Submitted: 8 months ago.
Category: Cadillac
Customer: replied 8 months ago.
I have tried new dash integration module and rear integration modules, (unable to program since on key on) also tried new remote control door lock receiver.( Was unable to enter key program mode)Nothing worked. I feel as something is not waking the system up.
Customer: replied 8 months ago.
(Any parts I have tried, I have reinstalled original parts back)
Expert:  Pete replied 8 months ago.
My name is ***** ***** I am a professional here at Just Answer. I noticed that your question had not received a response and thought I would see if you still need help with this.I apologize for the delay and I hope I can still assist you with this here. This sounds like a major power loss issue here.I have seen issues with loose or corroded or damaged battery cables at the battery or to where they run and connect as well as at the fuse panels.I would start with checking the battery cables and connections for any issues and if any issues are found they would need repaired to correct this fault here.If these are checked and found to be o.k. let me know so we can continue from here. If more help is needed, use the reply tab to continue our conversation. If no further assistance is needed, kindly rate my service.You can rate at any time and we can continue to work on your question as this will not close out your question.Keep in mind in some cases it can be difficult to fully diagnose or help repair your vehicle without seeing it and I work on delivering the best possible answer from what I see to work with.Thanks Pete
Customer: replied 8 months ago.
Battery connections are tight, and clean. I have performed pin tests at all modules listed above and all connections were tight.
Expert:  Pete replied 8 months ago.
Are the fuse panels receiving voltage (at or near 12 volts DC) at their power wire feed input at all?
Customer: replied 8 months ago.
Yes, all 3 fuse blocks have good battery voltage.
Expert:  Pete replied 8 months ago.
This is a difficult question for me to answer here myself.I will open your question up for others here to see if someone else can assist further on this as there may be others here that may have more info on what to check or do with this issue.I hope you can get this resolved with ease.No need to reply to my last post here unless it is a last resort as it will keep your question locked to me and others will not be able to view it.If you feel you want to continue to work with me on this feel free to reply at any time but keep in mind in some cases it can be difficult to fully diagnose or help repair this without seeing your vehicle.Thanks Pete
Expert:  Amedee replied 8 months ago.
Hello and welcome! Different expert here. Can I start by getting your VIN? Thank you!
Customer: replied 8 months ago.
I've been looking into the communications wiring. More specifically jx201 and jx300 thinking maybe it's a wake up issue. My vin is 1G6DW67V180104189
Expert:  Amedee replied 8 months ago.
Thank you for that information. Which modules on board the vehicle are you able to communicate with?
Customer: replied 8 months ago.
As of right now since I have keyless ignition Nothing turns on I cannot get into key on/acc mode. If I manually turn on run/crank relay (r/r fuse block) and power up circuit 3, instrument cluster turns on and I can get access to engine/pcm codes. Multiple communication faults. (This is why I started looking into data communication schematics). Cannot access communication with any other module. My tech2 asks for key on.
Expert:  Amedee replied 8 months ago.
Thank you for that information. I will do some digging and reply back shortly
Expert:  Amedee replied 8 months ago.
Ok, sorry for the delay! Let me explain how this starting circuit works. The ignition switch sends a signal to the instrument cluster. The cluster sends a signal to the ECM over the data circuit and then the ECM grounds or activates the starter relay. When this happens, the contacts inside the relay close and allow power through the relay down to the starter. So, this means that ANYTHING that disrupts this chain of events can and will prevent the engine from starting. ECM or cluster not communicating or working properly can and will prevent the engine from starting. This is what I believe is going on. So we need to start by checking powers and grounds going into the ECM and cluster and then checking the BUS communication circuit to see if it is gettins shorted out by a bad module. I suspect you could just have a bad ECM or a bad instrument cluster.
Customer: replied 8 months ago.
Ok just so Im sure we r on the same page, my ignition switch button does not light up at all, when I open the car door nothing turns on. I will check power and grounds at Pcm and remove instrument cluster when I get home tonight and check.
Expert:  Amedee replied 8 months ago.
YES, this means nothing is turning on. It could be the cluster, ECM or even a bad ignition switch.
Expert:  Amedee replied 8 months ago.
I am going to log off line for a bit but will be back on line tonight. I will be looking forward to your reply!
Customer: replied 8 months ago.
Ok, so I went ahead and checked the Pcm for battery voltage at X2 pin 56. Good 12v. no other constant B+. Grounds good.
Expert:  Amedee replied 8 months ago.
And is the ECM communicating with your scanner with the key on?
Customer: replied 8 months ago.
I also went ahead and ohmed out the gmlan wires from the Ipm to the instrument cluster, to the Rcdlr in the trunk al ohm out ok.
Expert:  Amedee replied 8 months ago.
Excellent!
Customer: replied 8 months ago.
I cannot turn key on with the keyless button no lights on button and no response when opening doors. When I manually jump the run/crank relay in the right rear fuse block I can communicate with pcm but that's about it.
Expert:  Amedee replied 8 months ago.
Is the ECM communicating with your scanner with the key on?
Customer: replied 8 months ago.
Even when jumping relay still no lights on keyless button
Expert:  Amedee replied 8 months ago.
Right. I understand. I need to know if the ECM is communicating.
Customer: replied 8 months ago.
Well I got this outa it
Customer: replied 8 months ago.
I can get some access. It seems as if when I press the acc button I hear clicking from underhood and allows me some type of access to ecm
Customer: replied 8 months ago.
(Posted by JustAnswer at customer's request) Hello. I would like to request the following Expert Service(s) from you: Live Phone Call. Let me know if you need more information, or send me the service offer(s) so we can proceed.
Customer: replied 8 months ago.
Accidentally hit that call button
Customer: replied 8 months ago.
Codes I found
U2108
U2172
U2167
U2164
U2163
U2135
U2130
U2600
Expert:  Amedee replied 8 months ago.
Thank you for that informataion. The thrid pic on top.. it says instrument cluster? Does that mean you were communicating with the instrument cluster when the U2108? If so, this is a good sign. This means that the cluster is communicating. It says no communication with the ABS/TCS module. Maybe the ABS module is shorting out the entire system..
Customer: replied 8 months ago.
When I go to communicate with any of the modules it comes up no comm. I hit the acc button( no lights) I hear clicks from underhood, and I'm able to communicate with some things. That was the instrument cluster.
Expert:  Amedee replied 8 months ago.
Try to disconnect the connector going to the ABS module. Turn the key off for a few minutes and then back on and see if communication resumes with all of the modules. If so, the ABS module is bad and needs to be replaced. I have to leave for work. I do work all day today. I will be back on line tonight. I will be looking forward to your reply!
Customer: replied 8 months ago.
ok I'll try and unplug the abs connector before work reconnect the battery and see if I get any life out of the car.
Expert:  Amedee replied 8 months ago.
Hello! Just got home. Any luck disconnecting the ABS module?
Customer: replied 8 months ago.
Ok... Wow that was a pain disconnecting on the ground, sucks working without a lift. Lol. So unplugged the abs module. Reconnected battery, still no response from the car. Open door, no dash lights, no lights on ignition button still.
Expert:  Amedee replied 8 months ago.
Ok, this is progress. Not that this is good but we at least know that the problem is NOT the ABS module. I suspect it is going to be a bad ECM or a bad instrument cluster.
Customer: replied 8 months ago.
Question for you, the engine Ecu, I know on the Mercedes I work on they are married to the vehicle and cannot be reprogrammed to another vehicle. Can I get a used Ecu and reprogram it to my car? And without programming it, if I plug it in I should see some change in the cars reaction if the Ecu was the fault?
Expert:  Amedee replied 8 months ago.
A new or used one will need to be programmed to the vehicle. You should be able to reuse an old one.. but again, I would verify this with the guys at the dealership just to be sure. YES, once a new one is replaced, you should see be able to see the improvment right away provided the old ECM was in fact bad.
Customer: replied 8 months ago.
I found a used ecm with same part number, out of same year STS. But positive I'll be able to reprogram information into it? (It's been awhile since I've dealt with sps programming) haven't done it since 02 so If it reacts to the used pcm I'll probably have it towed to the dealer for programming.
Customer: replied 8 months ago.
If this is the case I'll order it asap and let you know my results when I plug it in.
Expert:  Amedee replied 8 months ago.
Again, you will have to verify all powers and grounds going into the ECM and call the dealership and ask them if it can be reprogrammed.
Customer: replied 8 months ago.
i will call in the am, but regardless, whether i get a used or even if i decide to buy a new one- i should have some type of improvement/ at least ignition switch lights (if this is the problem)
Expert:  Amedee replied 8 months ago.
I suspect you have a problem on the high speed GM lan serial data BUS circuit. Its got to be one of the modules connected to this circuit. Here is a list of modules on this circuit. High Speed GMLAN Serial Data LineThe GMLAN serial data communications circuit on this vehicle is in a linear topology. The following modules are connected to the link, in order from data link connector (DLC) to the end of the linear configuration:The instrument panel module (IPM)The electronic suspension control (ESC) module, with F85The communication interface module (OnStar), with UE1The dynamic headlamp leveling (DHL) device, with TR7The electronic brake control module (EBCM)The transmission control module (TCM)The engine control module (ECM)
Expert:  Amedee replied 8 months ago.
Data Link Communications Description and OperationCircuit DescriptionThe communication among modules is performed through the low speed and high speed GMLAN serial data circuits. The modules that need real time communication are attached to the high speed GMLAN network. The instrument panel module is the gateway between the networks. The purpose of the gateway is to transfer information from one network to another. The gateway will interact with each network according to that network's transmission model. High Speed GMLAN Circuit DescriptionThe data link connector (DLC) allows a scan tool to communicate with the high speed GMLAN serial data circuit. The serial data is transmitted on 2 twisted wires that allow speed up to 500 Kbps. The twisted pair is terminated with two 120 ohms resistors, one is internal to the engine control module (ECM) and the other is internal to the instrument panel module (IPM). The resistors are used to reduce noise on the high speed GMLAN bus during normal vehicle operation. The high speed GMLAN is a differential bus. The high speed GMLAN serial data bus (+) and high speed GMLAN serial data (-) are driven to opposite extremes from a rest or idle level. The idle level which is approximately 2.5 volts is considered a recessive transmitted data and is interpreted as a logic 1. Driving the lines to their extremes adds 1 volt to high speed GMLAN serial data bus (+) and subtracts 1 volt from high speed GMLAN serial data bus (-) wire. This dominant state is interpreted as a logic 0.Two different outputs are used by IPM to activate the high speed GMLAN bus:Accessory wake up, active in all power modes when IPM is awake except Crank and in a remote start requestHigh speed communication enable, active in all power modes when IPM is awake and in a remote start requestThe accessory wake up signal wakes up the ECM and the transmission control module (TCM) only. This output is disabled in Crank power mode for internal fail enable of the ECM and TCM. The high speed communication enable signal wakes up all the other modules on the high speed GMLAN bus.
Customer: replied 8 months ago.
ok so we said not ebcm, i dont' have F85, Tr7, i'll unplug the communication interface ue1 and see if that makes a change, the Tcm is on the valvebody unit on this car correct? ( so ill hope i dont need to go there lol)
Expert:  Amedee replied 8 months ago.
You got it! Here are the wiring diagrams for this circuit. One of these modules are shorting out.
Expert:  Amedee replied 8 months ago.
I am glad I can help! It has been a pleasure working with you. Please dont forget to honor your good faith deposit by rating my answer as "Excellent Service" for assisting you today. Please let me know if you have any further questions.
Customer: replied 8 months ago.
i'll run outside and disconnect the communication module now, and respond with update. otherwise i'll order a ECU and respond back to you when it arrives, hopefully it all works out. and no worries i wont forget to leave you an excellent svc rating
Expert:  Amedee replied 8 months ago.
Sounds good! Good luck! Fingers crossed!!
Customer: replied 8 months ago.
ok so no change with communications module disconnected. ordering ecu and i'll message back when it arrives. have a good night
Expert:  Amedee replied 8 months ago.
Sounds good! You too!
Customer: replied 8 months ago.
used ecu arrived, plugged it in, same, no response from anything.
Customer: replied 8 months ago.
for me to test if there is an open in communication through the tcm, can i jump pins 10&14 (circuit 2500) together and 11&13 (circuit 2501) on the tcm connector?

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