Cadillac Owners Forum banner

1 - 18 of 18 Posts

·
Registered
1989 Cadllac Brougham
Joined
·
202 Posts
Discussion Starter #1
Greetings, i am diagnosing the tps on my car and the reference voltage is just 3,58v the tps voltage at idle is 0,14 and wide open is 2,54. Carb is new, ecm is new, tps is replaced. I am suspecting the wiring here. What would be the easiest way of re wiring the tps contact?
 

·
Registered
87 Brougham, 1969 Calais, 95 FWB, 07 SRX, 07 ESV
Joined
·
4,246 Posts
the TPS may need to be adjusted. There is an adjuster screw that is hidden under a plug (needs to be drilled out) on the carb right near the TPS plug. You need a special tool to adjust it.
It's like a really long skinny socket with a nut welded onto it that you can turn with a wrench. I have one in my tool box somewhere. Anyways, you adjust it by tapping into the wires and hooking up a
multimeter and watch the voltage as you turn the adjuster. When you get to the right voltage, manually push the throttle to WOT with your hand and watch the voltage and verify that it is to spec at WOT as well.
If not, you may need to do the adjustment again.

Check some info posted in this thread:
http://www.cadillacforums.com/forums/rwd-19xx-1984-deville-fleetwood-1985/200501-tps-voltage.html

Here:
http://www.cadillacforums.com/forums/rwd-19xx-1984-deville-fleetwood-1985/190585-need-help-bad-urgent.html

I also had some pictures...I'll see if I can find them.

----------

I think the voltage at idle should be like .41 per those threads so an adjustment might be in order!
 

·
Registered
1980 FBC
Joined
·
980 Posts
I thought the reference voltage is a current limited 5 volt source that gets pulled down by the TPS.

I could be wrong.

If I'm not wrong there could be a poor connection somewhere not supplying the proper voltage. The ECM could be sillly also.
 

·
Registered
1989 Cadllac Brougham
Joined
·
202 Posts
Discussion Starter #4 (Edited)
*UPDATE*

I traced the TPS cables back to the ECM and checked the voltage directly at the harness, still 3,58 reference volt, switched to my old ECM, still TPS reference voltage is 3,58 volt. After removing the harness and checking the voltage directly on the ECM terminals i knew that there had to be something wrong within the harness wiring. After a long time of testing i found a and the only way the TPS BLUE and BLACK wire can be connected to the ECM to receive 5.0 volt, and that is according to the picture below. If there are any kind soul that would have the time to post a picture of your ECM harness here i would be delighted



11291882_10206249790944352_588415901_n.jpg




This is how the harness was wired originally, wired like that the TPS receives 3,58 Volt. I have yet not figured out where the gray cable goes to. It could be the MAP sensor. This would explain why the mechanic could not adjust the TPS voltage to the right level when i had a new carb installed . Since then i have got my hands on a re manufactured ECM with 2 years warranty, a new TPS sensor and acquired expensice E4MC carb TPS adjustment tools. I drained my battery in the process (courtesy lights are hungry) i get back to you as soon as i have it charged and ready.

PS i bought the car with 4 error codes, i have re routed half of the vacuum system which somebody had put together completely wrong, and i have managed to get all codes out except code 22 which is TPS sensor voltage too low.




11291882_10206249790944352_588415901_n.jpg
 

·
Registered
1980 FBC
Joined
·
980 Posts
Err. It doesn't take much to sink that voltage. A poor connection or wet condition will do it.

I assume you are measuring with a high impedance volt meter???
 

·
Registered
1989 Cadllac Brougham
Joined
·
202 Posts
Discussion Starter #9
Found a ECM harness diagram in my Service Information manual, now i am sure on that the wiring in the harness is ok (changed it back)


11262346_10206250050430839_947509952_n.jpg
 

·
Registered
1989 Cadllac Brougham
Joined
·
202 Posts
Discussion Starter #10 (Edited)
These are live values i get at idle ...
The TPS reference voltage is now 5.0v measured at the sensor contact, i will try to re adjust the TPS
ForumRunner_20150520_183248.png





ForumRunner_20150520_183237.png
 

·
Registered
1989 Cadllac Brougham
Joined
·
202 Posts
Discussion Starter #11
With TPS contact disconnected tps Voltage reads just 2,5 volt, acording to my service information manual it whould read at least 4, if below 4 volts check circuit 417 for short to ground. i will replace the entire TPS contact with wires and get back to you, i am hopeful!
 

·
Registered
87 Brougham, 1969 Calais, 95 FWB, 07 SRX, 07 ESV
Joined
·
4,246 Posts
Going all out looking for a fix. I love reading these troubleshooting threads :)
 

·
Registered
1980 FBC
Joined
·
980 Posts
I don't know if that circuit goes through the bulkhead but there could be moisture there. Another good one is idiots who stab through insulation to check circuits and a few years later they rust where the wound is.
 

·
Registered
1989 Cadllac Brougham
Joined
·
202 Posts
Discussion Starter #16
I have ordered a new tps connector and will re wire the sensor contact
 

·
Registered
1989 Cadllac Brougham
Joined
·
202 Posts
Discussion Starter #17
I finally did it. After a 2 years and a lot of work the Check Engine light has gone out. Replaced ECM, Carb, Vacuum hoses, TPS, TPS connector and wires. Engine now runs like a dream, smooth like a spirit in plaid slippers. Thanks a lot to you guys in here!!
 

·
Registered
1980 Eldorado, 1974 Talisman, 2004 Volvo C70, 1975 Fleetwood 'd Elegance
Joined
·
7,958 Posts
Hey Jeppi, you are the one that rocks here!
You did the hard part!
Thanks for the new "expression" too! that's not one I have heard in the states!
 
1 - 18 of 18 Posts
Top