dash cluster earth help
Thread Starter
Heel & Toe
Joined: Nov 2005
Posts: 18
Likes: 0
From: Cambridge Cambridgeshire
dash cluster earth help
I've got a problem with dash doing strange things when cold. (flashing, speedo going up to 30mph while standing still) Also it fades away sometimes then comes back. banging door close also seem to have an effect on it. Looks like it is earth problem and i've read there's an black/white wire on left hand side of transmision. My question is where exactly is this wire and do you need to jack the car up to get to it or can you see it from the top?
I've heard there's also a dodgy earth connection inside the cluster, how diffucult is it to get to that?
Thanks for help.
I've heard there's also a dodgy earth connection inside the cluster, how diffucult is it to get to that?
Thanks for help.
Race Director
Joined: Aug 2000
Posts: 14,130
Likes: 7
Cruise-In II Veteran
Im willing to bet you have some loose grounds someplace or a problem with the connectors in the dash itself coming apart.Older C4 digital dashes seem to have a problem with the solders in the circuit board getting old and cracked.
However,you need to also be sure the dash connectors itself is tight and secured and not coming loose.They do have lock tabs on them but some people discard them when doing service and forget to replace them when plugging stuff back in.
Start from there and see what you can find.There are also several ground wires attched on the side of the engine block above the oil filter area and also on the back of the passenger side head held on by a bolt.
Im not sure if those are where the grounds you need to check would be but its some of that I know of to check for any problems.
However,you need to also be sure the dash connectors itself is tight and secured and not coming loose.They do have lock tabs on them but some people discard them when doing service and forget to replace them when plugging stuff back in.
Start from there and see what you can find.There are also several ground wires attched on the side of the engine block above the oil filter area and also on the back of the passenger side head held on by a bolt.
Im not sure if those are where the grounds you need to check would be but its some of that I know of to check for any problems.
Racer
Joined: Jun 2000
Posts: 428
Likes: 1
From: Friendswood Texas
Probably is an earth problem (gound to us Yanks). I went through this with my 86. There are two ground connections. One is routed to a bolt on the frame (passenger side just in front of the door, under the carpet and sill plastic. The other goes through the firewall and connects to the engine block. This connection goes through a "temperature" switch on the firewall, next to the brake pedal. Some of the posts on this forum have suggested that we by-pass this temperature switch. I did this and it really helped. I seem to remember that the ground to the engine block was for power and the one on the interior passenger side was the sensor ground. I'd check them both.
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
Ambient switch usually isn't a problem, but one of the two grounds is (up until '89 when GM changed the routing); notably where it passes through the main harness connector at the battery. It's in the bottom and water can get in there creating corrosion. Easy solution is to solder the grounds together at the cluster assuming that one of them is still good. Pins D1 & D3.
