connexion2005

iTrader: (49)

Ok so I have been head over heels trying to track down an annoyance on a project I'm working on. The POWER ACCY fuse and the components on it cause a major malfunction in the gauge cluster. It creates a massive draw on the battery as well. I've checked ALL GROUNDS and they are fine. I have not checked individual little grounds that split from the main ones to create each individual ground for the cluster connector due to lack of a schematic. The radio and gauges do not work! The cluster produces bogus flickerings and is all kinds of messed up. The OBD II port forwards all the necessary statistics to a data logger so I know the car runs fine and the PCM is fine. The wiring appears to be completely legit and the factory radio is in the car. So here is my million dollar question!

CAN THE BCM AFFECT THE GAUGE CLUSTER READOUTS AND RADIO GOING ON AND OFF!?

THE PREVIOUS OWNER TOLD ME HE HAD THIS PROBLEM AS WELL SINCE I BOUGHT THE CAR WITH A BLOWN MOTOR FROM HIM. THIS PROBLEM EXISTED BEFORE I SWAPPED IN THE NEW MOTOR. He also said sometimes when it would short out the gauges went crazy, the radio turned off and the power windows would not work. The radio and windows problem I've directly correlate with the BCM and a solder joint issue.

Thanks in advance guys!

WhiteBird00

iTrader: (4)

Well, yes and no. The BCM is not connected to the gauges in the instrument cluster in any way. However, the BCM is connected to the various warning lights in the cluster and is responsible for the self-test of those lights that occurs when you first start the car.

The BCM also controls the following circuits:
- seat belt warning light
- interior courtesy lights
- power locks
- keyless entry system
- optional alarm system
- VATS (vehicle anti theft system... the resistor pellet in the key)
- retained accessory power (radio and power windows)
- hatch release
- audible warnings (seat belt, lights on, etc.)

connexion2005

iTrader: (49)

Alrighty then. So is there any way a bad RAP or BCM could cause this problem? The previous owner mentioned that his windows and radio would not work occasionally so of course I'm looking at the BCM solder issue for that but I'm still trying to add up why the gauges would have issues.

WhiteBird00

iTrader: (4)

That depends - if the problem is that the lights in the cluster are flashing and/or doing strange things then it is possible the BCM could be the cause. If the gauges themselves (temp, oil pressure, etc.) are acting strangely then it is not the BCM because it isn't involved in those circuits.

The RAP circuit is not the cause... it is a symptom. RAP affects only the radio and the power windows. However, if there is a general BCM failure (other than just the cracked solder problem) then it could affect other circuits in addition to the RAP circuit.

connexion2005

iTrader: (49)

The ENTIRE cluster malfunctions as soon as the POWER ACCY fuse is inserted. The tach and speedo spike to max and then return to not move at all and the entire cluster will blink randomly. You have been such a huge help with your knowledge. Any ideas at this point. I'm really considering pulling the dash to investigate the wiring because this is ridiculous. I'm going to pull the BCM and inspect it regardless and swap in a known good RAP because I saw schematics that the cluster was in some way tied to that. It was an older schematic from a 96 model though and I'm working on a 99.

connexion2005

iTrader: (49)

Well I pulled the BCM out on lunch break and the bottom of the T solder points is DEFINITELY corroded and a bit broken up looking. I'll heat that back up and ensure it's solid a bit later and report back if it had any effect on my gauges.

connexion2005

iTrader: (49)

Well the radio is now working which is a plus. However my cluster is still not working correctly. I noticed that with the key in run when I released the e-brake, it would make the RAP automatically start clicking every 1 second. At this point I've tested known good RAP's and BCM's in this car with no success! WTF!!! I'm going to pull the intake to ensure the ground on the passenger head is connected and actually ground correctly. I mean hell where do I go from here!?

WhiteBird00

iTrader: (4)

I'm a little confused here because you keep referring to the BCM and RAP as though they were two separate things. The RAP circuit is just one of a number of circuits contained in the BCM. There is no separate box for RAP.

The symptoms make me wonder if perhaps there is more wrong with the BCM than just the solder joints on the RAP circuit. It could be that the BCM is fried. Do you have access to another one (borrow from a friend) that you could use to test?

connexion2005

iTrader: (49)

I've tested with a known good BCM and I apologize for posting about a seperate "RAP" box. The box I was calling a RAP module is actually behind the radio in the dash. It has a blue and black connector and can be accessed through the radio hole once it's removed. That box is ticking (resetting it seems like) with all these problems. Also I have no ground on the smaller connector going to the radio. Is there any way you can help find out where that ground is stemming from? I know in the end it leads to the drivers kick panel ground location but something seems to be poorly grounding and I need to follow that wire all the way back.

Also is there a schematic that will tell me the pinout and voltages of the gauge cluster when the key is in the RUN position and off?

Here is a pic of the pigtail going to the radio with no ground I'm talking about...
The pin that is labeled as ground is not producing a ground on my test light. The radio works now after the BCM fix but the clock and illumination still does not work.

WhiteBird00

iTrader: (4)

That box is the Daytime Running Light (DRL) module. It controls the front turn signals, DRLs, automatic headlights (Camaro), and BRAKE warning light in the cluster. I can't imagine how it could cause this problem but have you tried unplugging it and seeing if the problem goes away?

That harness goes to the optional CD changer. If you don't have a changer, none of those connections go anywhere. You'll find the other end of the harness wrapped in foam and taped to the left hatch speaker wires. Don't worry about it.


A1 - Not Used
A2 - Not Used
A3 - PINK - Fused Ignition Feed
A4 - Not Used
A5 - TAN/WHITE - Brake Warning Indicator Lamp Input
A6 - Not Used
A7 - Not Used
A8 - BROWN/WHITE - Service Engine Soon Indicator Lamp Input
A9 - Not Used
A10 - ORANGE - Fused Battery Feed
A11 - Not Used
A12 - LIGHT BLUE/WHITE - Left Turn Indicator Input
A13 - PURPLE/WHITE - Fasten Seat Belt Indicator Input
A14 - Not Used
A15 - Not Used
A16 - Not Used
A17 - LIGHT GREEN - High Beam Indicator Input

B1 - BROWN - Park Lamp Feed
B2 - Not Used
B3 - GRAY - Security Indicator Input
B4 - Not Used
B5 - PURPLE/WHITE - Fused Ignition Feed
B6 - GRAY - Class 2 Serial Data
B7 - ORANGE/BLACK - Rear Compartment Lid Ajar Indicator Lamp Input
B8 - DARK GREEN/WHITE - Vehicle Speed Signal
B9 - GRAY - Instrument Cluster Lamp Feed
B10 - DARK BLUE/WHITE - Right Turn Indicator Input
B11 - BLACK - Ground
B12 - Not Used
B13 - Not Used
B14 - TAN - Oil Pressure Gauge Input
B15 - BLACK/WHITE - Ground
B16 - Not Used
B17 - Not Used


See above.

The clock and digital display are protected by the POWER ACCY fuse so you would have nothing if that fuse is removed.

connexion2005

iTrader: (49)

The DRL module ticks when the brake handle is let down. Essentially it seems like at the point the e-brake goes off, the DRL module is attempting to pass power on to the necessary objects such as the DRL's but is failing to get a good ground so it just begins to reset and click. I swapped in a known good DRL module with the same result but I did not attempt to unplug it. I'll try that when I get home...

I was able to get the info you posted for the cluster it's just that I don't know approximate voltages to expect but then again that may not be important at a time like this.

I've never walked away from an issue but this one is pushing me. I'm half way tempted to just pull the dash and start following wiring but I'm not even sure how beneficial that would be. Thanks for clearing up the CD changer harness thing because that helps me rule that out.

I assume the DRL module grounds over at the driver kick panel as well. Do you have any knowledge of how to follow it's grounds towards that common ground?

Whether I figure this out or not WhiteBird you have been a phenomenal help during the process...

slo_lt1

iTrader: (2)

i am having a similar problem does your cluster do something like this??

connexion2005

iTrader: (49)

That is almost exactly what I'm experiencing. When you do things like turn a turn signal on does it sporadically blink with the signal? You have a bit more functionality than I do but not much...lol. Let's figure this out man!

connexion2005

iTrader: (49)

Although it's probably un-related. Here are the Daytime Running Light "DLR" module pinouts...

I changed the title as well to make it easier to search for...

slo_lt1

iTrader: (2)

finally!!i havnt been able to find ANYBODY else with this problem. i was reading what white bird said about the DRL module were exactly is that located? my blinkers wont come on and my headlights are always on if the key is on even if i try to turn them off nothing happens.

i also hear a random ticking in my dash somewere and a ticking from one of the fuse boxes under the hood. just remembered when i put the blinker on the rear blinker illuminates but doesnt blink front does nothing and it isnt burnt out.

does this happen randomly for you or all the time?do your rpms fluctuate like mine when it happens? and when driving the car and it starts to happen does the car buck uncontrollably?

EDIT:also my emergency brake light is always on my ebrake cable is broken is that the cause or does that have to do with the DRL thing to?

connexion2005

iTrader: (49)

That's just it you have more functionality from your gauges but less from your lighting. All my lighting will work on demand but I have no tach, speedo, temp or fuel level. My battery reading is incorrect well as my oil pressure. I haven't driven the car lately but from my memory I don't think this played any role in the way the car drove. I'm going to check the ground at the DRL module and unplug it to see what happens. Thank god I have 4 Ls1 fbodies to test out different parts with. Although my gf gets pissed when I take BCMs and clusters out of hers...lol.

I'll make a video to show you how my car acts in a bit on lunch break.

WhiteBird00

iTrader: (4)

The DRL module grounds through the shared instrument panel ground at the stud behind the left side kick panel under the dash.

connexion2005

iTrader: (49)

I want to throw this out there as well but the blue PCM connector pack has a slightly broken up blue plastic piece. I didn't think it would make much of a difference but would that connector being damaged cause enough issue to cause something like this?

connexion2005

iTrader: (49)

Well that's good for sure so that sucks...I mean I suppose it's possible they have a damaged ground somewhere in between but that's a huge guess and not really worth pulling the dash for.

slo_lt1

iTrader: (2)

also just noticed if i start the car then shut it off after a few seconds i start to hear a very rapid ticking somewhere in the dash. cant really tell were its coming from sometimes it sounds like its behind the radio, sometimes below the steering wheel, sometimes in the kick panel dunno if than has anything to do with this problem???