Help with 1990 Volvo 745 GL Regina Gauge Cluster Wiring

[Coe]

Hi all,

I just picked up my first ever car, a 1990 745 GL Regina, and have been doing some work on it. Yes I know, my interior is dirty I am working on cleaning that. I took the gauge cluster out to replace my broken clock with a clock I pulled off an 89 GLE at a junkyard. When removing my gauge cluster, I foolishly forgot to correctly mark which wires went where. The big connectors are quite obvious, but I am struggling with the 3 smaller wires: a black/white, a red/white, and a yellow/white+violet. I found a wiring diagram and I think I know where the latter 2 but I have no idea where the black/white wire is supposed to go. A part of me thinks that it is an extra wire maybe for ABS which my car does not have, but I would greatly appreciate any help. Thank you!

 

[nordmaschine]

Red/white is tacho. Goes to a male spade connector on the back of it. Try driving it without those other two, and report back what/if is not working.

 

[DET17]

I might have a 90 wiring diagram for a 745 ..... and mine is also Rex/Regina. Don't know that the instrument cluster cares.

If you don't have it sorted in a couple days, PM me and I'll look when I'm home next.

 

[Coe]

Thank you guys for your responses! I tried plugging it back in and attacked the red/white wire to what I labeled A on my photo and I attached the yellow/white+violet to the area I labelled B. Interestingly, after starting the car nearly stalls, jumps rpms to save itself, repeats this cycle, then inevitably stalls. This does not happen with the cluster removed. Is it possible that the clock from a different car is making this happen? I may have also swapped the fuel gages, I honestly can't remember. Would either of those cause this problem, or do I have the wiring wrong? Thank you again for your help!

 

[bobxyz]

Try disconnecting the red-white wire (behind the tach) and see if it runs better. That wire goes to the coil "-" terminal and could cause weak spark if something's wrong in the cluster.

The yellow and white-violet wires go to the back of the speedometer for cruise control and the ECU.

I have no idea what the black-white wire is.

 

[Coe]

Thanks for the suggestion. I’ll try that this afternoon. Does it matter which of the two prongs in each group I connect each of the wires to? They don’t seem to be differentiated in any way. Thank you!

 

[bobxyz]

The 2 side-by-side prongs in each group are connected together (maybe made out of 1 piece of metal), use either one.

 

[Coe]

Tried running it without the tach wire and same thing, stalls out after about 15 seconds. Is it possible a messed up the whole cluster while taking it apart and need a new one?

 

[MasterBlaster]

1 - Did it run before you viciously ripped the cluster out while laughing maniacally?

2 - Bad cluster shouldn't make the engine die. My spare came from an 89 740 wagon a customer was scrapping. All I did was "jump" a 194 light bulb between plug terminals C4 and D4 (warning light + ignition 12v) so the alternator would fire up and charge. He had no problem driving it to its death.

 

[Coe]

I could barely tell because I was so busy laughing, but yes it drove just fine before I took it out. Drove it around a few days without the cluster in (never once stalled right after turning on) and learned the hard way that the alternator engages from that light on the dash lol. Stalled out at a major intersection.

At this point I think I’ll try replacing the battery next, but what makes me doubt that will do anything is the fact it runs completely fine without the cluster.

Regarding that diagram, should I have a wire going to the part marked H? I don’t think there’s a wire that fits that connector and I just want to make sure I’m not blind. Thank you.

 

[MasterBlaster]

it runs completely fine without the cluster.

Hmmmm....

Regarding that diagram, should I have a wire going to the part marked H?

I don't think mine has anything going there, though I haven't yanked it out in a while.
Probably just an auxilliary power outlet for a function I don't have.

 

[Coe]

So then at this point I'm sure that my wiring is correct given that which of the two prongs and the orientation of the wire does not matter. I'm first going to try a cluster I got from a junkyard and see how that fairs. From there, I'll try a new battery and then from there everything under the sun related to the fuel system.