Question about Base to TC/Sport cluster swap. (SOLVED)

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Question about Base to TC/Sport cluster swap. (SOLVED)

April 24, 2005, 08:42:48 AM

The cluster was already swapped when I got the blue Bird and has a really strange problem with the gas gage. When switched on it reads normal(I think, is nearly full of gas and reads between 3/4 and full), but when I start the engine, the gage drops to empty. I haven't really tried to trouble shoot this problem, just checked the EVTM.. I'm suspecting the connections are wrong. Anybody had a similar problem when they did this swap???

Re: Question about Base to TC/Sport cluster swap.

Reply #1 – April 24, 2005, 09:03:42 AM

Never heard of that one. Might be a ground problem - the sender might be finding a ground through the windings of the fuel pump, and when you start the engine the fuel pump is energized, taking that path to ground away.

Re: Question about Base to TC/Sport cluster swap.

Reply #2 – April 24, 2005, 09:13:57 AM

Good point Carmen, I'll check that out(DRATS... Now I gotta crawl into the trunk)... :)

EDIT.... MAJOR IDEA.... All I have to do to check that possibility is ground the fuel pump relay at the EEC test connector.

Re: Question about Base to TC/Sport cluster swap.

Reply #3 – April 24, 2005, 09:46:34 AM

Well I grounded the EEC test connector so the pump would run contionusly and it still reads almost full, started it up and the gage headed south again... I'll have to troubleshoot it later, they are having a Suffolk Dragway(closed in '92) reunion car show over in Portsmouth today. Will be some old race cars there from the '60s & '70s, I'm gonna go look at some old drag cars... :D

Re: Question about Base to TC/Sport cluster swap.

Reply #4 – April 25, 2005, 10:55:34 AM

Holy ! Is that Tom asking a tech question?! I smell a 'sticky' on this thread.

If the gas tank has been changed, it's possible the previous owner installed one from a car with a digital cluster. In that case everything would read opposite on an buttstuffog gauge. My buddy did that with his/my old '88 XR7...I warned him to double check the cluster from the donor car but he didn't. And now when the car is full, the gauge reads empty. What a loser.

Anyway, his gauge did the same thing as what you're describing. Since I knew all the conditions, it was easy to figure out what was wrong. Just my $.02.

Re: Question about Base to TC/Sport cluster swap.

Reply #5 – April 25, 2005, 06:12:15 PM

You sure bout that Eric???? My gage reads OK with just the ignition sw on, it only falls back to "E" when I start the car.... If it had the wrong sending unit would it not still read empty with the ign sw on..

I'm gonna check the resistance back to the sending unit and see what it is...

Re: Question about Base to TC/Sport cluster swap. (SOLVED)

Reply #6 – April 25, 2005, 08:25:41 PM

OK I fixed it.... and killed the charging system... :D

I found the white/yellow wire from the gas gage sending unit wasn't even connected, just taped up. So why did the gage read nearly full when switched on, then dive when the engine started??? The red green wire to excite the alternator was connected to the gas gage, so when the charging system came up, the gage no longer had a ground path. Made for a hellva charge indicator.....

Hey the gas gage is reading full... The charging system just quit !!! :hick: WTF???

Anyway I connected a 194 bulb(put it in the ABS position) from the alternator exciter wire back to switched 12v and now it charges again. Also with the correct wire connected to the gas gage it works as well...