2005 Rainier, E40 ECM and PWM fan- no start after flash

[V8 Supra Builder]

SOLVED: Short-attention span summary: I damaged the C1 connector and this caused the ECM to lose communication over the serial data line. Once I replaced the connector, the truck started.

I bought this truck recently and wanted to dump the clutch fan so I can use an electric one. Doing some reading on the subject, the 2005 E40 ECM allows for either a clutch fan (Rainier/Envoy/Trailblazer etc), discrete (relay) fans (GTO), or a PWM fan (C6 Corvette).

I'll try & attach a pinout comparison I pulled from the service manuals for each (Excel spreadsheet).

What I did was use ECM pin C1-36, which in the Rainier is the fan clutch control wire, and I just unplugged the fan connector. I re-pinned a new wire in the C1-36 opening and taped off the old one. The new wire goes to the new fan's PWM terminal. The wiring diagram shows it goes to a fan relay terminal and it appears to be a +12V feed for the relay's coil- the opposite terminal goes to ground. I do not see a class 2 data connection for the fan clutch. It has a total of 5 wires:
A: Chassis ground
B: Clutch supply voltage (+12V), from above relay
C. Low reference for Hall sensor, goes to ECM
D. Cooling fan speed signal, goes to ECM
E. 5 volt reference to Hall sensor from ECM

I have attached the cooling schematic as a PDF.

On the C6, C1-36 is the PWM output or fan speed control.

The fan is out of a Mercedes and I verified it operates with the same PWM settings as the C6 by using a PWM generator. It's a really simple setup, 2x heavy gauge power & ground, and a small gauge wire for the PWM.

I reflashed the calibration using the fan settings for the C6. The truck will no longer start. I reflashed the stock calibration, and also did a write entire trying both. Same problem remains. I pulled the battery (both cables) for a few hours and left the headlights on to draw out any holdover power. No change.

I sent in a ticket via HP Tuners and no one could figure out what happened, but they said the ECM seems to be OK. There is an older thread where the BCM in a 2007 Tahoe went out after a Gen 4 ECM reflash. My symptoms are very similar. In that instance, the member put in a new BCM, flashed it, and his truck started. He reported no communication withe BCM via his Tech 2 tool.

A generic code scanner gave me two ECM DTC codes, loss of communication with the BCM or U1064. There was also a loss of comm with the climate control, U1152.

Where I'm at now is trying to get one of the VCX Nano Tech 2 adapters (Tech2Win) to work with my laptop, truck, and the Delco SPS site so I can program modules. I bought a programming subscription, but it gives me an error when I try to connect to flash modules (that's another battle). Using it as a diagnostic tool, I get a U1000 Class 2 Serial Datalink malfunction error on most modules. The odd thing is the BCM responds to all inputs such as headlight switch position, so unlike the member with the 2007 Tahoe, I can communicate with the BCM. I can also ping all modules. I'm going to try a new BCM as soon as I can get my adapter to connect to GM's SPS.

This is worse than trying to put a Chevy V8 into a BMW!!!

2005 E40 Pinouts Rainier-C6-GTO.xlsx

2005_Rainier_cooling_circuits.pdf

[blindsquirrel]

Is VATS still enabled? Does it not crank, or not start? Have you tried the security relearn procedure? Have you flashed it with a file with VATS disabled? You really need to be able to see real scan tool data on the security system status. If this were a failed-flash situation you wouldn't be able to communicate with the ECM using any tool.

Since it's not a failed-flash thing, you can skip the disconnecting the battery and letting it sit stuff. Also forget about the fan conversion for now, disconnect any wiring changes you've made temporarily until it's back to working again.

[blindsquirrel]

After you get the no-start(no-crank?) issue sorted, here's the wiring diagram edited to show the changes needed for a PWM or brushless fan on '05-'06 GMT360s. You have to remove the solid state relay and replace with a jumper between #4 & 5. In stock form, the relay is swapping the ECM's switched ground to a switched +12v. The PWM controllers need the raw switched ground as it comes out of the ECM.

[V8 Supra Builder]

I had disabled the VATS, it made no difference. I get no cranking. I also tried the manual security relearn (3x 10 minute chunks) with no difference. I scanned some more stuff with the Tech2Win. On the BCM security section I wrote down this data for the Passlock:
Passlock volts: 1.29
Passslock code: 3
Passlock ignition cycles: 0
Passlock power: Inactive
Passlock state: Monitor passlock

I don't have anything to compare any of this to so as to know if it is good or bad.

When I was pinging the modules, at first the BCM gave me an intermittent 0. Everything else was a 1. After I pinged all, the BCM output a 1 like the rest. Still no start though.

...here's the wiring diagram edited to show the changes needed for a PWM or brushless fan on '05-'06 GMT360s. You have to remove the solid state relay and replace with a jumper between #4 & 5. In stock form, the relay is swapping the ECM's switched ground to a switched +12v. The PWM controllers need the raw switched ground as it comes out of the ECM.

Thanks for the advice on the fan wiring. I did not see an attachment for your relay diagram. I'm trying to understand how jumping the terminals works in relation to getting a PWM signal from the ECM.

Using the GM diagram, removing the relay and jumping 4 and 5 means I'd have to reconnect the OEM C1-36 wire, which goes to terminal 5- otherwise terminal 4 would be disconnected. Terminal 4 is the +12V to the clutch. With the relay removed and jumper installed, this puts the C1-36 output (#5) onto the white wire that goes to the clutch control (#4). I don't see where there is any electrical difference there to how I have it wired now.

I sketched this out comparing OEM wiring vs the jumper vs what I have done and will attach it as a PDF. Let me know what I'm missing.

OEM_vs_relay_jumper_vs_C1-36_mod.pdf

[blindsquirrel]

Sorry, the forum auto-deleted it, I tried to post it as the full size image instead of the dumb thumbnail (why isn't there an option to do that anyhow without having to try silly workarounds?).

2006 E40 - SPAL brushless.png

You're right, it's the same thing as what you did, you just need a jumper instead of a whole new wire run. End result is the same.

If you do a fresh read of the ECM and compare it to the file you flashed, are there any differences? Any chance other wires in C1 were disturbed and not seating properly now? Verified the new wire you added is isolated from GND and especially B+? I think this is a back-to-basics issue, not some freak flashing-the-ECM-killed-the-BCM thing. That's about as likely as a rogue cosmic ray strike.

Can you scan live data with the fake-MDI*/Tech2Win? You should be able to see ign switch position, crank request, security status, etc.


*I have the same setup, so that's not meant as an insult

[V8 Supra Builder]

Thanks again for your advice. I spent some time with it tonight & I am pretty sure I FUBAR'd the C1 connector. I can't get all of the pins to seat properly and I cracked part of the inner piece when I replaced the pin. Wish I had known about that jumper wire option! I'm going to order a new connector (#88953346 for reference) and do a wire for wire swap. I did notice one of the problem children was a dark green wire #16, which sure enough is serial data.

These are a true PITA compared to the Gen 3 connectors I'm used to working with, but at least now I have a clue as to what happened.

[blindsquirrel]

Yeah, DON'T disassemble the whole connector body, (lolsob) I made that mistake the first time I had one apart. Just remove the lock and release the pins one at a time. If you take the cage off everything goes everywhere.

[V8 Supra Builder]

I found the C1 connector and related parts at EFI Connection for a better price than the dealers. I made a PDF of where each wire goes so I can use it while underhood. I'll attach it in the event someone else down the road needs it. I'm still looking for advice on removing the terminals. I found a couple of special tools that say they are for "Micro 64". No doubt that is what I need since the terminals won't slide out with the green lock removed. If I can get the parts & tool this upcoming week maybe I can get it back on the road.

Any terminal removal tips are appreciated.

2005_Rainier_C1_wire_colors_positions.pdf

UPDATE- BIG SECRET INFORMATION!!! What's your clearance level?

I found a Harley service manual online that on ONE PAGE tells how to remove micro 64 terminals- with photos (see attached PDF below). The reason why these will not pull out after the green lock is removed is because there is a primary terminal lock in the connector that must be released via the tool. You can use either a Delphi 15381651-2 or a Harley H-45928. These sell for around $20-30 from what I can tell. The process is fairly simple- find the microscopic hole between the pairs of terminals, insert and hold the tool, pull the terminal(s). It's not needed for pushing in new terminals.

Why this had not been posted here & elsewhere is beyond me. Knowing this would have saved me a connector. I'm going to post this in the 4th gen section for future reference.

Micro_64_terminal_removal.pdf

[V8 Supra Builder]

Squirrel, if you're still following this thread, I got everything done today - found I had to reflow the ABS module as well- and started the truck. I'm having an issue with the PWM fan. Mine is from a Mercedes C320. I tested the fan with a PWM generator @ 100 Hz and 128 Hz and it works the same as the C6 fan- 15% low, 90% high.

I see in some other posts you went through some PWM fan issues on your Envoy, so if you have some advice here I'd appreciate it.

When I start the truck with the AC on, the fan is running maybe 20% or so. The problem is the fan does not speed up as the coolant warms up. I hooked up the VCM scanner and saw the temp rise well above 210.

I tried to attach my HPT file but it won't upload for some reason.

I then copied the Rainier "State vs desired" and "Output control vs state" tables. I also set the fan for 128 Hz- I had it @ 100 before. Reflashing this, the fan seems to work opposite from what it is supposed to do. I can control it via the scanner. When I set it at 90% it slows way down. At 15% it speeds up.

I know I can reverse the input values on the ECT and AC pressure tables (such as substituting 15 for 90 and vice-versa), but I thought if you had some insight into those two tables maybe I'm doing something wrong there.

[blindsquirrel]

You should be able to copy the fan settings direct from any stock 2005 Corvette repository file (that's the only C6 that used the E40). Lots of different makes from that era (even some Fords (spit!), I believe) all used the same Siemens PWM module so that shouldn't be an issue. You have the ECM pin C1 #36 going direct to the PWM box control input, no more relay in there inverting the signal, right?

I'm using a SPAL brushless so my settings ended up being slightly different due to the crossbreeding. Don't copy what I used, copy the '05 C6.

[blindsquirrel]

BTW, I finally got a set of connector cores to investigate the unused pins in the E40 and the DIY-pointed-stick method still works. Poke-pull-pull, poke-pull-pull, etc. Improvised poking device is .031" dia. It drops in about .300" freely, deeper than that is where it begins to push the tab back.

[V8 Supra Builder]

You should be able to copy the fan settings direct from any stock 2005 Corvette repository file (that's the only C6 that used the E40). Lots of different makes from that era (even some Fords (spit!), I believe) all used the same Siemens PWM module so that shouldn't be an issue. You have the ECM pin C1 #36 going direct to the PWM box control input, no more relay in there inverting the signal, right?

I'm using a SPAL brushless so my settings ended up being slightly different due to the crossbreeding. Don't copy what I used, copy the '05 C6.

I did copy those settings. Per your advice, I pulled the relay and added a Metri Pack jumper wire on 4 & 5. I made a quasi-plug & play setup by cutting off the OEM fan connector and then cutting away all but the white wire on the shroud side. I ran it down the shroud and added a Weather Pack single connector so the shroud can be removed. I used dielectric grease on all of the pins.

What I forgot was I think the Mercedes fan (it has a built-in controller) may use the opposite polarity PWM output (pos or neg, can't remember which right now). I know if that is the case, the fan will run low @ 90% and high @ 15%. I tested a Volvo XC90 fan for another project and found it was the opposite PWM polarity of the Mercedes fan.

What I need to figure out is what if anything those "State vs desired" and "Output control vs state" tables do for a PWM fan. For the time being, I'll set the fan up with 90% for low and 15% for high and see what happens.

[blindsquirrel]

"built in controller"... OK, link to or part numbers or year/make/model for what hardware this is. I was assuming it was the standard bellybutton Siemens box, apparently not.

[V8 Supra Builder]

It's from an early 2000s Mercedes C class, I think the model was a 320. The data I got was from a YouTube video:

https://www.youtube.com/watch?v=5LQMDRCO5nk

I found another thread that explained the "states" on the fan screen:

Set stage 0 to have both fans off.
Set stage 1 to have fan 1 on and fan 2 off.
Set stages 2-7 to have both fans on.

Based on the info there, it appears these two tables are for discrete (relay) controlled multiple fans.

However, the OEM Rainier's electro-mechanical fan had different data in both tables than did the C6:
On the "State vs desired %", the Rainier went up in groups of 12:
12
24
36, etc up to 84, then in the lower groups it went from 10 to 80.

The C6 has all zeros there.

In the "output control vs state", the Rainier had ones and zeroes, and I noted there are 8 states, which includes 0:
For fan output 1, it was 0-1-0-1-0-1-0-1 (every other pattern)
Fan output 2: 0-0-1-1-0-0-1-1 (groups of 2 pattern, 2x what was in fan output 1)
Fan output 3: 0-0-0-0-1-1-1-1 (groups of 4 pattern, again 2x what was in fan output 2)

The C6 had all ones in each box.

Clearly there is a connection here in that each table references states 0 through 7.

I'm still playing around with this, but for now I'm going to put in the inverse settings and road test it.

[V8 Supra Builder]

I road tested some more today & for the most part it went well. I had a MIL and on scanning it I saw P0171 and 0174 (banks 1 and 2 too lean). A search online showed some Gen 4 vehicles run rich after a reflash, so I zeroed out the injector tip temperature offset tables, reflashed the calibration, and I think that took care of the MIL.

EDIT- The MIL was caused by a vented catch can I had installed about the same time. I capped the vent and no more MIL.

The only issue I'm seeing now is the fan seems to operate fine (with the inversed numbers) off of ECT, but I'm seeing relatively high AC pressure that should speed up the fan but it's not spinning as fast as it should. I'll do some more reading on that.