Parrformance

So....got the adjustable thermostat and relay wired up, fans coming on around 160°F. Just need to know if I should tie into the high pressure side of the AC, and where to connect it in the relay.

For those of you who are more experienced in wiring relay circuits. I would like to use a Painless Adjustable fan controller. I would splice the 12Volts from the original Volvo pigtail at the air solenoid to the pin 30 on the relay. I would splice the other half to the 87a terminal, to allow for 12 volts to the air solenoid to shut off the fan until the thermostat trips the relay, if I have that right. (Normally Closed). I would expect as to the thermostat reaches set temp it would trigger the relay to open 87a and close 87 removing 12 volts from 87a and turning the fan on. If this all seems kosher, where and how should I add a wire to the high side switch on the AC?

I hope you recover soon. I had to take a break on the truck diagnosis to install a mini split in my son's garage. Oh and fix the drier, and replace the faucet in the camper and..... I hope to get back at it tomorrow. I would need to understand the tying into the high pressure switch for the AC.

I am pouring over multiple schematics. More importantly component location diagrams. The VED12d engine in my 2006 Volvo, manufactured 07/2005 is supposed to have a fan speed sensor on the front of the block near the fan clutch. Perhaps someone can explain why I do not see a sensor near the fan clutch, nor any wire looms near it either. I am getting a fan speed error on the display, AND a pre heat error. The fan solenoid Y35 and the Engine pre heat relay RLY42 share 12Volts from fuse 70 leg B through Splice SP592B. Ground leg out comes from ECM connector B pin 49 through Connector EM pin 11

Thank you Randy, this is what I was looking for. I realized I needed no volts for fan on and 12 volts for fan off. I did a little research and realized I could use a double throw relay to accomplish what I needed. I ran out of time last night, but it seems as though I have 5 volts on the ground leg of the fan solenoid circuit. I also have no pre heater function, and the pre heat relays and fan solenoid share power from fuse 70. I had hoped for an issue with this leg, but continuity and voltage are all good from fuse to solenoid. Will check the ground side from ECM to solenoid next. Hoping to find the phantom voltage there. I think I will check the EM connector next for green crusties. Both the 12v leg and ground leg pass through this connector. Thanks RandyA

For those that know, is there a difference between Electronic fan drive, and the air activated fan drive? I suspect that the used ECU that I purchased, nay have been on a truck with a variable speed electronic fan. My truck has an electrically activated air solenoid, normally closed for fan control. I assume these parameters may be adjustable in the ECM? I do have access to a Diesel Laptops computer. We used the computer to reset the Max speed parameters.

Replaced the ECM with a used one. The used one had this issue on startup. I plan to add an adjustable fan controller until I figure out the issue. Diesel Computer says wiring or relay. I can jump 12v to the solenoid and turn the fan off. With the fan controller I ordered, it looks like I can swap a normally closed relay in place of the normally open one. This will power the solenoid when the fan doesn't need to be on.

For those that have rewired your engine fan to kick on either from a switch on the dash for a thermostat, can you share what method you used I would like to use a thermostat the switch the fan on at the appropriate temperature so that I don't have to think about it or switch it on from a switch on the dash

The used ECM worked, the oil pressure guage is working again. The Truck is no longer de-rated. I am having a couple of new issues, engine fan speed error, and the two intake air heater codes. I am hoping not an ECM issue but perhaps a wiring problem. Tackle these tomorrow. I recently replaced the engine fan solenoid and the short pigtail harness, so going to start there first.

Hi-Tech has horrific reviews as well. Anyone have first hand knowledge of swapping a used ECM into a Volvo and what else will need to be done?

Looks like I am going to give Hi-Tech Electro ECM in Irving Texas a try with the ECM repair for my Volvo VED12D motor. Anyone have any reason that I should find another repair place? Looks like TRUCK ECM and ECM King do not repair the Volvo ECU part# 20561256.

I still have my P-pump 12 valve 98 Ram with NV4500 5 speed. The "Holy Grail" of the pre electronic motors that started in 98 1/2 model year. I plan to keep it. No need to get rid of a perfectly good durable drive train, until the Dodge jiggly bits fall off.

Did you have anything adjusted while they had your ECM Jim?

Thanks Darryl&Rita, Found this one too: https://goecm.com/

Does anyone know if there is a rebuilder for the engine computer on these volvo? I have voltage on the appropriate pins, my grounds check good as well. The bus wires have continuity between the VECU, and the ECU. The ECU appears to be bad, I suspect a bad solder joint as it worked intermittently but now dead. I might be willing to crack it open and look for bad solder joints, probably one at pin 60 or 57 on the B connector side. I would prefer to send it off for repair, I think.

Facts don't care about your feelings. Thomas Macdonald

Yes pm your e-mail. With a request for the manual.

NVM, I found it on the VORAD schematic. MCFC 52 is the location of wire 6209 You may all go back to your regularly schedule programming.

I have one single wire on the MCFC passthrough connector, that has become dislodged. Dislodged on the inside cab half of the large passthrough connector. I believe it came out of pin 52, but I am not sure. It seems to be marked 6209. Anyone have a schematic of each side of the MCFC Connector?

Seems to have needed a good cleaning.

Bingo

Thank you, I suspect no 12v or loss of ground to the Engine ECU. The Truck ECM has no communication with the Engine ECU currently. Saw the grounds, I plan to clean them next. Thanks for the suggestion.

Thank you, I suspect no 12v or loss of ground to the Engine ECU. The Truck ECM has no communication with the Engine ECU currently.